Full of Holes

Abstract

Cell Biology![Figure][1] CREDIT: MADDUGODA ET AL., CELL HOST MICROBE 10 , 464 (2011) The endothelium acts as a barrier between tissues, but can sometimes be transiently perforated in health and disease by transcellular tunnels. These tunnels can allow the passage of leukocytes to sites of infection, but can also be exploited by invading pathogens. Maddugoda et al. studied the effects of the edema toxin (ET) from Bacillus anthracis on endothelial integrity. In mice, intravascular injection of ET led to an increase in endothelial permeability and the generation of transcellular tunnels via its effects on cyclic-AMP signaling. After this permeabilization, the transcellular tunnels were “healed” by the action of the MIM (Missing in Metastasis) protein, which, in response to the increased membrane curvature induced by the tunnels, triggered the production of actin-rich membrane protrusions that seal the tunnel. This type of transient permeabilization and resealing of the endothelial barrier probably regulates the overall permeability of the endothelium, and perturbation of this balance by the action of pathogens can be key to their successful colonization of the host. Cell Host Microbe 10 , 464 (2011). [1]: pending:yes