title: Inhibition of ROCK activity allows InlF-mediated invasion and increased virulence of Listeria monocytogenes.
abstract: Listeria monocytogenes is an intracellular bacterial pathogen that causes life-threatening disease. The mechanisms used by L. monocytogenes to invade non-professional phagocytic cells are not fully understood. In addition to the requirement of bacterial determinants, host cell conditions profoundly influence infection. Here, we have shown that inhibition of the RhoA/ROCK pathway by pharmacological inhibitors or RNA interference results in increased L. monocytogenes invasion of murine fibroblasts and hepatocytes. InlF, a member of the internalin multigene family with no known function, was identified as a L. monocytogenes-specific factor mediating increased host cell binding and entry. Conversely, activation of RhoA/ROCK activity resulted in decreased L. monocytogenes adhesion and invasion. Furthermore, virulence of wild-type bacteria during infection of mice was significantly increased upon inhibition of ROCK activity, whereas colonization and virulence of an inlF deletion mutant was not affected, thus supporting a role for InlF as a functional virulence determinant in vivo under specific conditions. In addition, inhibition of ROCK activity in human-derived cells enhanced either bacterial adhesion or adhesion and entry in an InlF-independent manner, further suggesting a host species or cell type-specific role for InlF and that additional bacterial determinants are involved in mediating ROCK-regulated invasion of human cells.
authors.affiliation: Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood, Boston, MA 02115, USA.
authors.forename: Marieluise
authors.initials: M
authors.lastname: Kirchner
authors.forename: Darren E
authors.initials: DE
authors.lastname: Higgins
mesh_terms: D000577:Amides / Q000494:pharmacology; D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D005260:Female; D006367:HeLa Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D008089:Listeria monocytogenes / Q000254:growth & development / Q000472:pathogenicity*; D008088:Listeriosis / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D024462:Myosin Type II / Q000037:antagonists & inhibitors / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D013045:Species Specificity; D014774:Virulence; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D000577:Amides; D001426:Bacterial Proteins; D047428:Protein Kinase Inhibitors; D011725:Pyridines; C108830:Y 27632; D054460:rho-Associated Kinases; D024462:Myosin Type II; D020742:rhoA GTP-Binding Protein