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Institute
The endoplasmic reticulum (ER) is the largest cellular organelle that undergoes constant turnover upon diverse functional demands and cellular signals. Removal of nonfunctional or superfluous subdomains is balanced by the parallel expansion and formation of ER membranes, leading to the dynamic exchange of ER components. In recent years, selective autophagy of the ER, termed ER-phagy, has emerged as a predominant process involved in ER degradation and maintenance of ER homeostasis. Identification of multiple ER-phagy receptors, many with additional ER-shaping functions, paved the way for our molecular understanding of ER turnover in different cells and organs. In this review, we describe the molecular principles underling the physiological functions of ER-phagy in maintaining ER homeostasis via receptor-mediated macroautophagy and elaborate current focus points of the field.
Calcium (Ca2+) elevation is an essential secondary messenger in many cellular processes, including disease progression and adaptation to external stimuli, e.g., gravitational load. Therefore, mapping and quantifying Ca2+ signaling with a high spatiotemporal resolution is a key challenge. However, particularly on microgravity platforms, experiment time is limited, allowing only a small number of replicates. Furthermore, experiment hardware is exposed to changes in gravity levels, causing experimental artifacts unless appropriately controlled. We introduce a new experimental setup based on the fluorescent Ca2+ reporter CaMPARI2, onboard LED arrays, and subsequent microscopic analysis on the ground. This setup allows for higher throughput and accuracy due to its retrograde nature. The excellent performance of CaMPARI2 was demonstrated with human chondrocytes during the 75th ESA parabolic flight campaign. CaMPARI2 revealed a strong Ca2+ response triggered by histamine but was not affected by the alternating gravitational load of a parabolic flight.