title: Vimentin and PSF act in concert to regulate IbeA+ E. coli K1 induced activation and nuclear translocation of NF-κB in human brain endothelial cells.
abstract: BACKGROUND
  IbeA-induced NF-κB signaling through its primary receptor vimentin as well as its co-receptor PSF is required for meningitic E. coli K1 penetration and leukocyte transmigration across the blood-brain barrier (BBB), which are the hallmarks of bacterial meningitis. However, it is unknown how vimentin and PSF cooperatively contribute to IbeA-induced cytoplasmic activation and nuclear translocation of NF-κB, which are required for bacteria-mediated pathogenicities.
  
  
  RESULTS
  IbeA-induced E. coli K1 invasion, polymorphonuclear leukocyte (PMN) transmigration and IKK/NF-κB activation are blocked by Caffeic acid phenethyl ester (CAPE), an inhibitor of NF-κB. IKKα/β phosphorylation is blocked by ERK inhibitors. Co-immunoprecipitation analysis shows that vimentin forms a complex with IκB, NF-κB and tubulins in the resting cells. A dissociation of this complex and a simultaneous association of PSF with NF-κB could be induced by IbeA in a time-dependent manner. The head domain of vimentin is required for the complex formation. Two cytoskeletal components, vimentin filaments and microtubules, contribute to the regulation of NF-κB. SiRNA-mediated knockdown studies demonstrate that IKKα/β phosphorylation is completely abolished in HBMECs lacking vimentin and PSF. Phosphorylation of ERK and nuclear translocation of NF-κB are entirely dependent on PSF. These findings suggest that vimentin and PSF cooperatively contribute to IbeA-induced cytoplasmic activation and nuclear translocation of NF-κB activation. PSF is essential for translocation of NF-κB and ERK to the nucleus.
  
  
  CONCLUSIONS
  These findings reveal previously unappreciated facets of the IbeA-binding proteins. Cooperative contributions of vimentin and PSF to IbeA-induced cytoplasmic activation and nuclear translocation of NF-κB may represent a new paradigm in pathogen-induced signal transduction and lead to the development of novel strategies for the prevention and treatment of bacterial meningitis.
authors.affiliation: Department of Pediatrics, Saban Research Institute of Children's Hospital Los Angeles, University of Southern California, Los Angeles, California, United States of America.
authors.forename: Feng
authors.initials: F
authors.lastname: Chi
authors.forename: Tao
authors.initials: T
authors.lastname: Bo
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Wu
authors.forename: Ambrose
authors.initials: A
authors.lastname: Jong
authors.forename: Sheng-He
authors.initials: SH
authors.lastname: Huang
mesh_terms: D021581:Active Transport, Cell Nucleus; D001812:Blood-Brain Barrier / Q000382:microbiology / Q000473:pathology; D001921:Brain / Q000382:microbiology / Q000473:pathology; D002109:Caffeic Acids / Q000494:pharmacology; D002465:Cell Movement; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism / Q000382:microbiology; D004926:Escherichia coli / Q000502:physiology*; D004927:Escherichia coli Infections / Q000276:immunology / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000378:metabolism / Q000502:physiology*; D055785:Gene Knockdown Techniques; D054884:Host-Pathogen Interactions; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism / Q000502:physiology*; D016920:Meningitis, Bacterial / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D055806:Microvessels / Q000473:pathology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020556:Neutrophil Infiltration / Q000187:drug effects; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D000072670:PTB-Associated Splicing Factor; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives / Q000494:pharmacology; D010766:Phosphorylation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D015398:Signal Transduction; D014404:Tubulin / Q000378:metabolism; D014746:Vimentin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D002109:Caffeic Acids; C096350:CusC protein, E coli; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D016328:NF-kappa B; D000072670:PTB-Associated Splicing Factor; D016601:RNA-Binding Proteins; D014404:Tubulin; D014746:Vimentin; D020928:Mitogen-Activated Protein Kinases; C055494:caffeic acid phenethyl ester; D010626:Phenylethyl Alcohol