title: Regulation of Toll-like receptor 2 interaction with Ecgp96 controls Escherichia coli K1 invasion of brain endothelial cells.
abstract: The interaction of outer membrane protein A (OmpA) with its receptor, Ecgp96 (a homologue of Hsp90β), is critical for the pathogenesis of Escherichia coli K1 meningitis. Since Hsp90 chaperones Toll-like receptors (TLRs), we examined the role of TLRs in E. coli K1 infection. Herein, we show that newborn TLR2(-/-)  mice are resistant to E. coli K1 meningitis, while TLR4(-/-)  mice succumb to infection sooner. In vitro, OmpA+ E. coli infection selectively upregulates Ecgp96 and TLR2 in human brain microvascular endothelial cells (HBMEC), whereas OmpA- E. coli upregulates TLR4 in these cells. Furthermore, infection with OmpA+ E. coli causes Ecgp96 and TLR2 translocate to the plasma membrane of HBMEC as a complex. Immunoprecipitation studies of the plasma membrane fractions from infected HBMEC reveal that the C termini of Ecgp96 and TLR2 are critical for OmpA+ E. coli invasion. Knockdown of TLR2 using siRNA results in inefficient membrane translocation of Ecgp96 and significantly reduces invasion. In addition, the interaction of Ecgp96 andTLR2 induces a bipartite signal, one from Ecgp96 through PKC-α while the other from TLR2 through MyD88, ERK1/2 and NF-κB. This bipartite signal ultimately culminates in the efficient production of NO, which in turn promotes E. coli K1 invasion of HBMEC.
authors.affiliation: Division of Infectious Diseases, Children's Hospital Los Angeles, Los Angeles, CA 90027, USA.
authors.forename: Subramanian
authors.initials: S
authors.lastname: Krishnan
authors.forename: Shuang
authors.initials: S
authors.lastname: Chen
authors.forename: Gianluca
authors.initials: G
authors.lastname: Turcatel
authors.forename: Moshe
authors.initials: M
authors.lastname: Arditi
authors.forename: Nemani V
authors.initials: NV
authors.lastname: Prasadarao
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004252:DNA Mutational Analysis; D004705:Endocytosis; D042783:Endothelial Cells / Q000382:microbiology*; D004926:Escherichia coli / Q000472:pathogenicity*; D054884:Host-Pathogen Interactions; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D025941:Protein Interaction Mapping; D011956:Receptors, Cell Surface / Q000378:metabolism*; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; C464645:GPATCH1 protein, human; D009419:Nerve Tissue Proteins; D011956:Receptors, Cell Surface; C495342:TLR2 protein, human; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D037521:Virulence Factors; C078167:OMPA outer membrane proteins