Fast and Long-Term Super-Resolution Imaging of Endoplasmic Reticulum Nano-structural Dynamics in Living Cells Using a Neural Network

Stimulated emission depletion (STED) microscopy is a super-resolution technique that surpasses the diffraction limit and has contributed to the study of dynamic processes in living cells. However, high laser intensities induce fluorophore photobleaching and sample phototoxicity, limiting the number of fluorescence images obtainable from a living cell. Herein, these challenges are addressed by using ultra-low irradiation intensities and a neural network for image restoration, enabling extensive imaging of single living cells. The endoplasmic reticulum (ER) is chosen as the target structure due to its dynamic nature over short and long timescales. The reduced irradiation intensity combined with denoising permits continuous ER dynamics observation in living cells for up to 7 h with a temporal resolution of seconds. This allows for quantitative analysis of ER structural features over short (seconds) and long (hours) timescales within the same cell, and enabled fast 3D live-cell STED microscopy. Overall, the combination of ultralow irradiation with image restoration enables comprehensive analysis of organelle dynamics over extended periods in living cells

Ubiquitination regulates ER-phagy and remodelling of endoplasmic reticulum

The endoplasmic reticulum (ER) undergoes continuous remodelling via a selective autophagy pathway, known as ER-phagy1. ER-phagy receptors have a central role in this process2, but the regulatory mechanism remains largely unknown. Here we report that ubiquitination of the ER-phagy receptor FAM134B within its reticulon homology domain (RHD) promotes receptor clustering and binding to lipidated LC3B, thereby stimulating ER-phagy. Molecular dynamics (MD) simulations showed how ubiquitination perturbs the RHD structure in model bilayers and enhances membrane curvature induction. Ubiquitin molecules on RHDs mediate interactions between neighbouring RHDs to form dense receptor clusters that facilitate the large-scale remodelling of lipid bilayers. Membrane remodelling was reconstituted in vitro with liposomes and ubiquitinated FAM134B. Using super-resolution microscopy, we discovered FAM134B nanoclusters and microclusters in cells. Quantitative image analysis revealed a ubiquitin-mediated increase in FAM134B oligomerization and cluster size. We found that the E3 ligase AMFR, within multimeric ER-phagy receptor clusters, catalyses FAM134B ubiquitination and regulates the dynamic flux of ER-phagy. Our results show that ubiquitination enhances RHD functions via receptor clustering, facilitates ER-phagy and controls ER remodelling in response to cellular demands

The Softening of Journalistic Political Communication: A Comprehensive Framework Model of Sensationalism, Soft News, Infotainment, and Tabloidization

Despite the scholarly popularity of important developments of political communication, concepts like soft news or infotainment lack conceptual clarity. This article tackles that problem and introduces a multilevel framework model of softening of journalistic political communication, which shows that the 4 most prominent concepts—(a) sensationalism, (b) hard and soft news (HSN), (c) infotainment, and (d) tabloidization, and, additionally, (e) eroding of boundaries of journalism—can be distinguished in a hierarchical model. By softening, we understand a metaconcept representing developments in political journalism that are observed on different levels of investigation, from journalism as a system (macrolevel) down to single media items (microlevel)

Personalization 2.0? – Testing the personalization hypothesis in citizens’, journalists’, and politicians’ campaign Twitter communication

This paper advances the research on personalization of political communication by investigating whether this process of focusing on politicians instead of political issues plays a role on Twitter. Results of a content analysis of 5,530 tweets posted in the run-up to the German federal election provide evidence that Twitter communication refers more often to politicians than to issues. However, tweets containing personal characteristics about political leaders play only a marginal role. When distinguishing among different groups of actors on Twitter (journalists, politicians, citizens), we find that citizens focus more on candidates than do journalists or politicians. Investigating the impact of a televised debate on Twitter communication, we observe that this person-centered event puts the focus on individual politicians instead of issues