Time for a quick roundup of some of the highlights from the latest issue of JCB.
Kawai and Amano describe a new function for the well-known breast cancer susceptibility gene BRCA1. As described in this summary, the researchers show that BRCA1 increases the maturation of microRNAs, by interacting with both primary microRNA transcripts and the DROSHA processing complex. The absence of BRCA1 causes a reduction in the levels of several microRNAs that dwindle in cancer tissues, and which may therefore usually act to suppress tumorigenesis.
BRCA1 is best known for its role in DNA repair, being recruited to double strand breaks after ubiqutination of the surrounding chromatin by ubiquitin ligases like RNF168. Poulsen et al. reveal a surprising function for the related ligase RNF169 – it actually competes with BRCA1 and other repair proteins for binding to ubiquitinated chromatin, thereby favoring break repair by homologous recombination rather than by non-homologous end joining. More here.
Our cover image compares two fibroblasts with and without ARPC3, a key component of the Arp2/3 actin nucleation complex. Suraneni et al. reveal that fibroblasts fail to make lamellipodial membrane protrusions in the absence of the Arp2/3 complex, and, without lamellipodia, the cells fail to migrate in a straightline for long distances. You can read more in this week’s In Focus.
Staying with cell migration, Steinberg et al. describe how the sorting nexin SNX17 helps recycle integrin adhesion molecules back to the cell surface instead of sending them to the lysosome for degradation. Cells lacking SNX17 have decreased levels of the alpha5 and beta1 integrins, and therefore move faster than control cells. You can read more in this summary.
There’s lots of other interesting papers elsewhere in today’s new issue – you can find them all on our table of contents – but today also sees the release of our latest biosights video podcast, which highlights the recent paper from Welf et al. describing how PI3-kinase signaling helps migrating cells reorient themselves by stabilizing branched protrusions at the cell’s leading edge. Senior author Jason Haugh explains all in the video here and, 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.
Cover image courtesy of Parveen Suraneni.