An image is of a single macrophage (a professional phagocyte) eating yeast particles (red). In green, F-actin is stained using phalloidin. Note the “bullseye” shape of the F-actin response.
Sergio Grinstein’s lab studies phagocytosis –the mechanism responsible for the clearance of pathogens, dead cells and macromolecular debris. The formation of the phagosome and its internalization requires tightly coordinated, localized actin assembly and disassembly. While mechanisms of actin assembly to drive advancing pseudopodia are well studied, the mechanism of actin disassembly was unknown. Screening a library of RhoGAP fluorescent fusion proteins, the Grinstein lab found 3 RhoGAPs that were recruited to large phagocytic cups in a phosphoinositide 3-kinase-dependent manner and were required for the completion of phagocytosis. The loss of any one of these RhoGAPs arrested phagocytosis at a stage where the actin-mesh is thick, indicating a non-redundant function of these GAPs. Their work was published in Nature Communications:
http://www.nature.com/ncomms/2015/151014/ncomms9623/abs/ncomms9623.html
