Die Zukunft der Arktis

"Der Entwicklung der Arktis wird seit einem knappen Jahr zunehmend größere Aufmerksamkeit geschenkt. Dies bezieht sich sowohl auf die mediale Berichterstattung als auch auf das Interesse Deutschlands, die zukünftigen Strukturen der politischen Zusammenarbeit in der Arktis mitzubestimmen. Die derzeitigen Entwicklungen und Perspektiven sind vielschichtig. Ausgelöst durch den Klimawandel haben bislang eisbedeckte, nun aber eisfreie Teile der Arktis dafür gesorgt, dass über eine dauerhafte kommerzielle Nutzung von Schifffahrtsrouten im Nordpolarmeer nachgedacht wird. Darüber hinaus werden in diesem Gebiet riesige, bislang nicht explorierte Öl- und Gasreserven vermutet, die aufgrund der Erderwärmung leichter zu fördern sein dürften. Im selben Atemzug wird über eine zunehmende Militarisierung der Arktis spekuliert, die den wirtschaftlichen Interessen der Anrainerstaaten Nachdruck verleihen soll. In den Debatten wird jedoch oft vergessen, dass die Polarregion von vier Millionen Menschen bewohnt wird, die zum Teil gegensätzliche Interessen verfolgen, und, darüber hinaus, dass mit dem Arktisrat sowie dem Euro-Arktischen Barents-Rat Institutionen geschaffen worden sind, die die Zusammenarbeit in zahlreichen Politikfeldern erleichtern sollen. Vor diesem Hintergrund fand in der Kanadischen Botschaft in Zusammenarbeit mit der politischen Abteilung der Botschaft und der Heinrich Böll Stiftung eine Konferenz statt, die die derzeitige Kooperation in der Arktis und die neuesten wissenschaftlichen Erkenntnisse näher beleuchtete." (Textauszug

The Rhetoric of Solidarity: Nature and Measurement of Social Cohesion in the Self-representation of Civil Society Organizations

Scholars have called to study how social cohesion is discursively negotiated and produced in communication behavior. However, empirical evidence remains scarce. In this study, we investigate to what extent and how civil society organizations (CSOs), part of the backbone of social integration in modern democracies, make references to social cohesion in their public self-portrayals. We develop a standardized measure for content analyzing the manifestation of social cohesion along three theoretical dimensions: social relations, connectedness, and orientation towards the common good. We apply our innovative content measure to the external communication of an original sample of nearly 800 CSOs in Germany, using their websites. Subsequently, we use data from an accompanying organizational survey of these institutions to investigate whether and how certain organizational features help explain variance in social cohesion rhetoric. Findings suggest that CSOs’ external communications employ themes from all key dimensions of social cohesion, revealing a fair amount of variation on all three subdimensions and a summary index of the overall strength social cohesion rhetoric. These different emphases are contingent upon various organizational characteristics, namely the spheres in which CSOs are primarily active, their locations, and their target groups. Whereas culturally and media-oriented organizations as well as sports clubs are largely reluctant to make references to social cohesion, politically active CSOs and those addressing socially disadvantaged communities tend to push more in this direction. The latter tend to operate in more professionalized structures, indicating that referencing social cohesion legitimizes these groups’ political and social purposes in the public sphere

Direct binding of hepatocyte growth factor and vascular endothelial growth factor to CD44v6

Volz Y, Koschut D, Matzke-Ogi A, et al. Direct binding of hepatocyte growth factor and vascular endothelial growth factor to CD44v6. Bioscience Reports. 2015;35(4): e00236.CD44v6, a member of the CD44 family of transmembrane glycoproteins is a co-receptor for two receptor tyrosine kinases (RTKs), Met and VEGFR-2 (vascular endothelial growth factor receptor 2). CD44v6 is not only required for the activation of these RTKs but also for signalling. In order to understand the role of CD44v6in Met and VEGFR-2 activation and signalling we tested whether CD44v6 binds to their ligands, HGF (hepatocyte growth factor) and VEGF (vascular endothelial growth factor), respectively. FACS analysis and cellular ELISA showed binding of HGF and VEGF only to cells expressing CD44v6. Direct binding of CD44v6 to HGF and VEGF was demonstrated in pull-down assays and the binding affinities were determined using MicroScale Thermophoresis, fluorescence correlation spectroscopy and fluorescence anisotropy. The binding affinity of CD44v6 to HGF is in the micromolar range in contrast with the high-affinity binding measured in the case of VEGF and CD44v6, which is in the nanomolar range. These data reveal a heparan sulfate-independent direct binding of CD44v6 to the ligands of Met and VEGFR-2 and suggest different roles of CD44v6 for these RTKs

Live cell imaging shows hepatocyte growth factor-induced Met dimerization

Koschut D, Richert L, Pace G, Niemann H, Mely Y, Orian-Rousseau V. Live cell imaging shows hepatocyte growth factor-induced Met dimerization. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH. 2016;1863(7):1552-1558.The canonical model of receptor tyrosine kinase (RTK) activation assumes that ligand-induced dimerization of inactive receptor monomers is a prerequisite for autophosphorylation. For several RTK families, recent results of fluorescence microscopy provided evidence for preformed receptor dimers that may or may not require ligand binding for kinase activity. Here we report, for the first time, the application of advanced quantitative fluorescence microscopy techniques to study changes in the oligomerization state of the RTK Met in response to stimulation by its endogenous ligand hepatocyte growth factor (HGF). We used inducible C-terminal fusions be, tween Met and enhanced green fluorescent protein (EGFP) or red fluorescent protein (RFP) in combination with fluorescence resonance energy transfer (FRET)-based fluorescence-lifetime imaging microscopy (FLIM) and fluorescence correlation spectroscopy (FCS). A small fraction of HGF-independent Met dimers appeared to be present in cells even at low receptor density. At high receptor density, both the fraction of Met dimers and the level of Met autophosphorylation increased in the absence of HGF. Stimulation with HGF at low receptor density significantly increased the fraction of Met dimers on live cells. We found no indications of Met oligomers larger than dimers. Our findings thus confirm a model of Met activation through HGF-induced dimerization and at the same time they support previous reports of Met dimers in unstimulated cells. The tools established in this work will be useful to further characterize the mechanism of Met activation and to define the contribution of co-receptors. (C) 2016 Elsevier B.V. All rights reserved

Internalization of Met Requires the Co-Receptor CD44v6 and Its Link to ERM Proteins

<div><p>Receptor Tyrosine Kinases (RTKs) are involved in many cellular processes and play a major role in the control of cell fate. For these reasons, RTK activation is maintained under tight control. Met is an essential RTK that induces proliferation, differentiation, migration, survival and branching morphogenesis. Deregulation of Met by overexpression, amplification or lack of effective degradation leads to cancer and metastasis. We have shown that Met relies on CD44v6 for its activation and for signaling in several cancer cell lines and also in primary cells. In this paper, we show that internalization of Met is dependent on CD44v6 and the binding of Ezrin to the CD44v6 cytoplasmic domain. Both CD44v6 and Met are co-internalized upon Hepatocyte Growth Factor induction suggesting that Met-induced signaling from the endosomes relies on its collaboration with CD44v6 and the link to the cytoskeleton provided by ERM proteins.</p></div