title: The class II phosphatidylinositol 3-phosphate kinase PIK3C2A promotes Shigella flexneri dissemination through formation of vacuole-like protrusions.
abstract: Intracellular pathogens such as Shigella flexneri and Listeria monocytogenes achieve dissemination in the intestinal epithelium by displaying actin-based motility in the cytosol of infected cells. As they reach the cell periphery, motile bacteria form plasma membrane protrusions that resolve into vacuoles in adjacent cells, through a poorly understood mechanism. Here, we report on the role of the class II phosphatidylinositol 3-phosphate kinase PIK3C2A in S. flexneri dissemination. Time-lapse microscopy revealed that PIK3C2A was required for the resolution of protrusions into vacuoles through the formation of an intermediate membrane-bound compartment that we refer to as a vacuole-like protrusion (VLP). Genetic rescue of PIK3C2A depletion with RNA interference (RNAi)-resistant cDNA constructs demonstrated that VLP formation required the activity of PIK3C2A in primary infected cells. PIK3C2A expression was required for production of phosphatidylinositol 3-phosphate [PtdIns(3)P] at the plasma membrane surrounding protrusions. PtdIns(3)P production was not observed in the protrusions formed by L. monocytogenes, whose dissemination did not rely on PIK3C2A. PIK3C2A-mediated PtdIns(3)P production in S. flexneri protrusions was regulated by host cell tyrosine kinase signaling and relied on the integrity of the S. flexneri type 3 secretion system (T3SS). We suggest a model of S. flexneri dissemination in which the formation of VLPs is mediated by the PIK3C2A-dependent production of the signaling lipid PtdIns(3)P in the protrusion membrane, which relies on the T3SS-dependent activation of tyrosine kinase signaling in protrusions.
authors: Department of Microbial Pathogenesis, Yale School of Medicine, Boyer Center for Molecular Medicine, New Haven, Connecticut, USA.
authors: Ana-Maria
authors: AM
authors: Dragoi
authors: Department of Microbial Pathogenesis, Yale School of Medicine, Boyer Center for Molecular Medicine, New Haven, Connecticut, USA herve.agaisse@yale.edu.
authors: Hervé
authors: H
authors: Agaisse
mesh_terms: D058947:Bacterial Secretion Systems / Q000502:physiology; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D022081:Cell Surface Extensions / Q000378:metabolism* / Q000382:microbiology; D004405:Dysentery, Bacillary / Q000473:pathology / Q000635:transmission; D019073:HT29 Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology; D008089:Listeria monocytogenes / Q000472:pathogenicity; D008088:Listeriosis / Q000473:pathology / Q000635:transmission*; D019869:Phosphatidylinositol 3-Kinases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000096:biosynthesis; D034622:RNA Interference; D034741:RNA, Small Interfering; D012763:Shigella flexneri / Q000472:pathogenicity*; D014617:Vacuoles / Q000378:metabolism / Q000382:microbiology*
chemical_list: D058947:Bacterial Secretion Systems; D018129:Phosphatidylinositol Phosphates; D034741:RNA, Small Interfering; C055525:phosphatidylinositol 3-phosphate; D019869:Phosphatidylinositol 3-Kinases; C546621:PIK3C2A protein, human