title: Analysis of Chlamydia caviae entry sites and involvement of Cdc42 and Rac activity.
abstract: In epithelial cells, endocytic activity is mostly dedicated to nutrient and macromolecule uptake. To invade these cells, Chlamydiaceae, like other pathogens, have evolved strategies that utilise the existing endocytic machineries and signalling pathways, but little is known about the host cell molecules involved. In this report, we show that within five minutes of infection of HeLa cells by Chlamydia caviae GPIC strain several events take place in the immediate vicinity of invasive bacteria: GM1-containing microdomains cluster, tyrosine-phosphorylated proteins accumulate, and intense actin polymerization occurs. We show that actin polymerization is controlled by the small GTPases Cdc42 and Rac, which become activated upon infection. Expression of dominant negative forms of these GTPases inhibits C. caviae entry and leads to abnormal actin polymerization. In contrast, the small GTPase Rho does not seem essential for bacterial entry. Finally, phosphatidylinositol 3-kinase activity is also required for internalization of C. caviae, probably downstream of the other molecular events reported here. We present the first scheme of the events occurring at the sites of invasion of epithelial cells by a member of the Chlamydiaceae family.
authors.affiliation: Unité de Biologie des Interactions Cellulaires, Institut Pasteur, CNRS URA 2582, 25 rue du Docteur Roux, 75015 Paris, France.
authors.forename: Agathe
authors.initials: A
authors.lastname: Subtil
authors.forename: Benjamin
authors.initials: B
authors.lastname: Wyplosz
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Balañá
authors.forename: Alice
authors.initials: A
authors.lastname: Dautry-Varsat
mesh_terms: D000199:Actins / Q000378:metabolism; D002689:Chlamydia / Q000378:metabolism*; D002690:Chlamydia Infections / Q000473:pathology; D002784:Cholesterol / Q000378:metabolism; D004705:Endocytosis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells; D020558:GTP Phosphohydrolases / Q000378:metabolism; D005799:Genes, Dominant; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D021962:Membrane Microdomains; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D010587:Phagocytosis; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D013997:Time Factors; D014162:Transfection; D014443:Tyrosine / Q000737:chemistry; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*; D020744:rac GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D000199:Actins; D002784:Cholesterol; D004791:Enzyme Inhibitors; D020558:GTP Phosphohydrolases; D019869:Phosphatidylinositol 3-Kinases; D019000:Phosphotyrosine; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D014443:Tyrosine; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins