In today's new issue of JCB, Sarkar and Zohn reveal that the ubiquitin ligase Hectd1 restricts the migration of cranial mesenchyme cells by inhibiting secretion of the protein chaperone Hsp90. Excess extracellular Hsp90 enhances the motility of Hectd1-deficient cells, potentially explaining why Hectd1-mutant mouse embryos have an abnormally organized cranial mesenchyme and neural tube closure defects. You can read more in this week's In Focus.
Byrd et al. describe how a microRNA fine-tunes a cell's response to ER stress. The researchers identify a microRNA called miR-30C-2*, which is upregulated when ER function is compromised and which targets the mRNA encoding XBP1, a key transcription factor that boosts ER capacity and cell survival. Blocking miR-30C-2* leads to increased XBP1 levels and enhanced cell survival in response to ER stress. More here.
And Roux et al. report a new way to screen for protein-protein interactions. Proximity-dependent biotin identification, or BioID, involves tagging proteins of interest with a promiscuous bacterial biotin ligase. When the resulting fusion protein is expressed in mammalian cells, nearby proteins are biotinylated, allowing them to be purified and identified by mass spectrometry. Roux et al. tested their approach with the nuclear lamina protein Lamin-A and identified both known Lamin-A interacting proteins and a novel nuclear envelope protein called SLAP75. Senior author Kyle Roux explains some of the advantages of this new approach here.
Today also sees the release of our latest biosights video podcast, in which Johan de Rooij discusses his lab's recent paper (Huveneers et al.) describing how the remodeling of endothelial intercellular adhesions takes place at a specialized subset of adhesions called focal adherens junctions. These adhesions recruit the mechanosensory protein Vinculin to resist tension from the actomyosin cytoskeleton and avoid excessive disruption when the junctions transiently remodel in response to angiogenic growth factors and inflammatory cytokines. You can watch the video below, or subscribe in iTunes. (And remember, if you'd like to present this paper to your colleagues in a journal club, you can download everything you need - including a pdf of the paper and a PowerPoint file of all the figures - by clicking here to download our monthly Journal Club Pack).
And, finally for today, this issue's review by Richard Hynes on the evolution of the extracellular matrix is the last in our Evolution series (all articles are freely available here). I'll let our reviews editor, Priya Prakash Budde, give you a quick series recap:
We have gotten a lot of great feedback on the series that started last summer with the evolution of membrane architecture (with a superbly funny title) from Field, Sali and Rout. This was followed by the evolution of cadherins from Oda and Takeichi. Masatoshi Takeichi discovered cadherins so it was a particular pleasure to have him write this article. Next up Carvalho-Santos et al. traced the origins of centrioles, cilia, and flagella; this article was even mentioned in Carl Zimmer's blog The Loom. We then moved on to the evolution of the cytoskeleton from Wickstead and Gull, and the nucleus from Wilson and Dawson. The penultimate article in the series, from Rojas et al., was the evolution of the Ras superfamily-a heroic effort analyzing this huge family of proteins. All of the articles use the amazing power of comparative genomics to provide a 'big picture' conceptual view of these topics. One of the authors even said that writing the article made them think differently about their research. I can't think of a better testimonial than that! So, please check out the series and let us know what you think.
Lots of other interesting papers in today's new issue as well. You can find them all on our table of contents, by clicking here.
Cover image courtesy of Anjali Sarkar.