Catálogo de publicaciones - revistas

<jats:title>Initiator for Coated Pit Assembly</jats:title> <jats:p> During clathrin-mediated endocytosis, it has been thought that the sensing and binding of the clathrin adaptor protein AP2 to cargo and lipids leads to the recruitment of clathrin, nucleating the formation of a clathrin-coated pit. <jats:bold> Henne <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="1281" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1188462">1281</jats:related-article> , published online 6 May) have now found that this process of AP2 binding may not in fact represent either the first or the nucleation event of endocytosis. Instead, ubiquitous proteins called FCHo1/2 (F-BAR proteins) bind to the plasma membrane and define the sites of endocytosis independently of AP2. The F-BAR protein can generate very low curvature and, at higher concentration, generates higher curvature like those required at the neck of budding vesicles. The C terminus of the protein has a mu-homology domain (with homology to the mu domain of the AP2 complex) that interacts with Eps15 and intersectin, and via these proteins recruits AP2, which further recruits clathrin. Thus, a curvature-inducing protein can act to nucleate clathrin-coated pit assembly during endocytosis. </jats:p>

<jats:title>Making Menorahs</jats:title> <jats:p> Highly branched neuronal processes are typical of numerous neurons. The mechanisms controlling the formation, maintenance and regeneration of neuronal trees are poorly understood. <jats:bold> Oren-Suissa <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="1285" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1189095">1285</jats:related-article> , published online 6 May) observed the development of extensively arborized neurite trees—menorahs—in two highly branched mechanosensory neurons in <jats:italic>Caenorhabditis elegans</jats:italic> . EFF-1, a fusion protein known to be important for cell fusion, played a key role in arborization. </jats:p>

<jats:title>Pharmacological Forgetting</jats:title> <jats:p> Extinction of conditioned fear forms a new memory in the infralimbic medial prefrontal cortex that is critical for subsequent retrieval of the extinction memory. Understanding the mechanisms that underlie this extinction-related plasticity could help in the treatment of anxiety disorders. By infusing BDNF (brain-derived neurotrophic factor) into the infralimbic cortex, <jats:bold> Peters <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="1288" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1186909">1288</jats:related-article> ) caused the extinction of conditioned fear, even without an extinction trial. In fact, BDNF infusion seemed to act as if an extinction training session had been given. Thus, the hippocampus is a likely source of the BDNF input to the infralimbic cortex, and individual differences in extinction memory may reflect variations in hippocampal BDNF content. </jats:p>

<jats:title>Sepsis Protection</jats:title> <jats:p> Sepsis is a serious medical condition characterized by an uncontrolled inflammatory response to infection. Sepsis often results in organ failure and/or death, and current treatments are not very effective. <jats:bold> Puneet <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="1290" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1188635">1290</jats:related-article> ) now show that the enzyme sphingosine kinase 1 (SphK1) may represent an important therapeutic target for the treatment of sepsis. SphK1 expression increased on human phagocytes in response to bacterial products and was also highly expressed on phagocytes from septic patients. Inhibition of SphK1 reduced the production of inflammatory mediators in vitro by human phagocytes stimulated with bacterial products. In vivo, pretreatment with small interfering RNA against SphK1 or a specific SphK1 inhibitor protected mice from death in two lethal models of sepsis. Protection was also seen when mice were treated with the SphK1 inhibitor up to 8 hours after sepsis induction, and this protection was enhanced if mice were given a broad-spectrum antibiotic. </jats:p>

<jats:title>Keeping Tabs on Second-Messenger Localization</jats:title> <jats:p> The prokaryotic second-messenger cyclic diguanosine monophosphate (c-di-GMP) is a global bacterial signaling molecule that controls the switch between motile or planktonic life-styles and sedentary or adhesive life-styles. Regulation by this second messenger has been associated with virulence traits, biofilm formation, and antibiotic tolerance. <jats:bold> Christen <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="1295" related-article-type="in-this-issue" vol="328" xlink:href="10.1126/science.1188658">1295</jats:related-article> ) engineered fluorescence resonance energy transfer–based sensors that enabled the visualization of c-di-GMP fluctuations in individual bacterial cells. Using the sensor, c-di-GMP distribution was found to change during the cell cycle in <jats:italic>Caulobacter crescentus</jats:italic> and <jats:italic>Pseudomonas aeruginosa</jats:italic> cells. </jats:p>

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<jats:p>The show includes a potential therapeutic target for sepsis treatment, reproductive success in field crickets, nuclear security, and more.</jats:p>