Thapsigargin, a tumour-promoting sesquiterpene lactone, selectively inhibits the Ca(2+)-ATPase responsible for Ca2+ accumulation by the endoplasmic reticulum (ER). Mobilization of ER-sequestered Ca2+ to the cytosol and to the extracellular fluid subsequently ensues, with concomitant alteration of cellular functions. Thapsigargin was found to serve as a rapid, potent and efficacious inhibitor of amino acid incorporation in cultured mammalian cells. At concentrations mobilizing cell-associated Ca2+ to the extracellular fluid, thapsigargin provoked extensive inhibition of protein synthesis within 10 min. The inhibition in GH3 pituitary cells involved the synthesis of almost all polypeptides, was not associated with increased cytosolic free Ca2+ concentration ([Ca2+]i), and was not reversed at high extracellular Ca2+. The transient rise in [Ca2+]i triggered by ionomycin was diminished by thapsigargin. Polysomes failed to accumulate in the presence of the drug, indicative of impaired translational initiation. With longer (1-3 h) exposures to thapsigargin, recovery of translational activity was observed accompanied by increased synthesis of the ER protein glucose-regulated stress protein 78 or immunoglobulin heavy-chain binding protein ('GRP78/BiP') and its mRNA. Such inductions were comparable with those observed previously with Ca2+ ionophores which mobilize the cation from all intracellular sequestered sites. Actin mRNA concentrations declined significantly during such treatments. In HepG2 cells processing and secretion of the glycoprotein alpha 1-antitrypsin were rapidly suppressed by thapsigargin. Ca2+ sequestered specifically by the ER is concluded to be essential for optimal protein synthesis and processing. These rapid effects of thapsigargin on mRNA translation, protein processing and gene expression should be considered when evaluating potential mechanisms by which this tumour promoter influences cellular events.

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Right-wing anti-establishment sentiment has enabled the mainstreaming of alternative media outlets across Europe and the United States. Earlier research has quantified the public recognition of these media actors through web traffic rankings, direct social media engagement (e.g., reactions, comments, shares), and topic overlap with establishment counterparts. We demonstrate a computationally scalable approach which (1) sharpens the analytical unit from topic (e.g., “immigration”) to specific news event (e.g., “migrant caravan traveling from Honduras”) and (2) enables the temporal ordering of the same news event appearing among media and politicians. Our method uses a combination of URL matching, word embedding similarity metrics, and network-based eventdetection techniques. We draw two main findings from a dataset of articles from 13 U.S. right-wing media outlets and (re-)tweets by congressional Republicans from 2016 to 2020. First, we identify a clear shift in politicians’ media consumption from left- to right-wing outlets. While established-right outlets made the largest gains (30% to 42% of all (re-)tweets), alternative-right outlets also grew from 2% to 5%. Second, we identify increasing content alignment among established- and alternative-right outlets as the URL-to-dyad ratio is almost halved over the time period. Finally, we present a proof-of-concept for detecting media outlets’ indirect political alignment.

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