University of Münster

About: University of Münster is a education organization based out in Münster, Germany. It is known for research contribution in the topics: Population & Catalysis. The organization has 35609 authors who have published 69059 publications receiving 2278534 citations. The organization is also known as: University of Munster & University of Muenster.

Ultraviolet Light Induces Apoptosis via Direct Activation of CD95 (Fas/APO-1) Independently of Its Ligand CD95L

Abstract: Induction of apoptosis in keratinocytes by UV light is a critical event in photocarcinogenesis. Although p53 is of importance in this process, evidence exists that other pathways play a role as well. Therefore, we studied whether the apoptosis-related surface molecule CD95 (Fas/APO-1) is involved. The human keratinocyte cell line HaCaT expresses CD95 and undergoes apoptosis after treatment with UV light or with the ligand of CD95 (CD95L). Incubation with a neutralizing CD95 antibody completely prevented CD95L-induced apoptosis but not UV-induced apoptosis, initially suggesting that the CD95 pathway may not be involved. However, the protease CPP32, a downstream molecule of the CD95 pathway, was activated in UV-exposed HaCaT cells, and UV-induced apoptosis was blocked by the ICE protease inhibitor zVAD, implying that at least similar downstream events are involved in CD95- and UV-induced apoptosis. Activation of CD95 results in recruitment of the Fas-associated protein with death domain (FADD) that activates ICE proteases. Immunoprecipitation of UV-exposed HaCaT cells revealed that UV light also induces recruitment of FADD to CD95. Since neutralizing anti-CD95 antibodies failed to prevent UV-induced apoptosis, this suggested that UV light directly activates CD95 independently of the ligand CD95L. Confocal laser scanning microscopy showed that UV light induced clustering of CD95 in the same fashion as CD95L. Prevention of UV-induced CD95 clustering by irradiating cells at 10°C was associated with a significantly reduced death rate. Together, these data indicate that UV light directly stimulates CD95 and thereby activates the CD95 pathway to induce apoptosis independently of the natural ligand CD95L. These findings further support the concept that UV light can affect targets at the plasma membrane, thereby even inducing apoptosis.

Frontline: Neuropilin-1: a surface marker of regulatory T cells

Abstract: CD4+CD25+ regulatory T cells (Treg cells) control immune responsiveness to a large variety of antigens. The isolation and therapeutic manipulation of Treg cells requires the use of reliable surface receptors that are selectively up-regulated in Treg cells. On the basis of global gene expression studies, we identified neuropilin-1 (Nrp1) as a specific surface marker for CD4+CD25+ Treg cells. Nrp1, a receptor involved in axon guidance, angiogenesis, and the activation of T cells, is constitutively expressed on the surface of CD4+CD25+ Treg cells independently of their activation status. In contrast, Nrp1 expression is down-regulated in naive CD4+CD25- T cells after TCR stimulation. Furthermore, CD4+Nrp1(high) T cells express high levels of Foxp3 and suppress CD4+CD25- T cells. Thus, Nrp1 constitutes a useful surface marker to distinguish Treg cells from both naive and recently activated CD4+CD25+ non-regulatory T cells.

Social media and political communication: a social media analytics framework

Abstract: In recent years, social media are said to have an impact on the public discourse and communication in the society. In particular, social media are increasingly used in political context. More recently, microblogging services (e.g., Twitter) and social network sites (e.g., Facebook) are believed to have the potential for increasing political participation. While Twitter is an ideal platform for users to spread not only information in general but also political opinions publicly through their networks, political institutions (e.g., politicians, political parties, political foundations, etc.) have also begun to use Facebook pages or groups for the purpose of entering into direct dialogs with citizens and encouraging more political discussions. Previous studies have shown that from the perspective of political institutions, there is an emerging need to continuously collect, monitor, analyze, summarize, and visualize politically relevant information from social media. These activities, which are subsumed under “social media analytics,” are considered difficult tasks due to a large numbers of different social media platforms as well as the large amount and complexity of information and data. Systematic tracking and analysis approaches along with appropriate scientific methods and techniques in political domain are still lacking. In this paper, we propose a methodological framework for social media analytics in political context. More specifically, our framework summarizes most important politically relevant issues from the perspective of political institutions and corresponding methodologies from different scientific disciplines.