Catálogo de publicaciones - revistas

<jats:title>To Die For</jats:title> <jats:p> The unfolded protein response (UPR) adjusts the protein folding capacity of the endoplasmic reticulum (ER) to match demand. UPR signaling requires IRE1α, an ER transmembrane kinase-endoribonuclease (RNase) that becomes activated by unfolded protein accumulation within the ER and excises a segment in XBP1 messenger RNA (mRNA) to initiate production of the homeostatic transcription factor XBP1s. However, if ER stress is irremediable, sustained IRE1α RNase activity triggers cell death. Severe ER stress activates the protease Caspase-2 as an early apoptotic switch upstream of mitochondria. However, the molecular events leading from the detection of ER stress to Caspase-2 activation are unclear. <jats:bold> Upton <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="818" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1226191">818</jats:related-article> , published online 4 October) now report that IRE1α is the ER stress sensor that activates Caspase-2, and does so through a mechanism involving non-coding RNAs. Under irremediable ER stress, IRE1α's RNase triggers the rapid decay of select microRNAs that normally repress translation of Caspase-2 mRNA, rapidly increasing Caspase-2 levels as the first step in its activation. </jats:p>

<jats:title>Bud, This Mitochondrion's for You</jats:title> <jats:p> How is organelle size adjusted to be appropriate for cell size? <jats:bold> Rafelski <jats:italic>et al.</jats:italic> </jats:bold> (p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="822" related-article-type="in-this-issue" vol="338" xlink:href="10.1126/science.1225720">822</jats:related-article> ) used a quantitative method for measuring mitochondria in living budding yeast cells and found that rather than using the apparently simplest mechanism of dividing the organelles equally among the mother and daughter cells, the cells adjusted the mitochondrial level in the bud, independent of the mother's own mitochondrial content, size, or age. </jats:p>

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