title: Heat shock protein gp96 interacts with protein phosphatase 5 and controls toll-like receptor 2 (TLR2)-mediated activation of extracellular signal-regulated kinase (ERK) 1/2 in post-hypoxic kidney cells.
abstract: Ischemia/reperfusion injury (IRI) induces an innate immune response, leading to an inflammatory reaction and tissue damage that have been attributed to engagement of the Toll-like receptor (TLR) 2 and 4. However, the respective roles of TLR2 and/or TLR4 in mediating downstream activation of mitogen-activated protein kinase (MAPK) pathways during IRI have not been fully elucidated. Here we show that extracellular signal-regulated kinase (ERK)1/2 is activated in both intact kidneys and cultured renal tubule epithelial cells (RTECs) from wildtype and Tlr4 knockout mice, but not those from Tlr2 knockout mice subjected to transient ischemia. Geldanamycin (GA), an inhibitor of heat shock protein 90 and reticulum endoplasmic-resident gp96, and gp96 mRNA silencing (siRNA), did not affect ERK1/2 activation in either post-hypoxic wild-type or Tlr4-deficient RTECs, but did restore its activation in post-hypoxic Tlr2-deficient RTECs. Immunoprecipitation studies revealed that gp96 co-immunoprecipitates with the serine-threonine protein phosphatase 5 (PP5), identified as a negative modulator of the mitogen extracellular kinase (MEK)-ERK pathway, in unstressed wild-type and post-hypoxic Tlr2-deficient RTECs. In contrast, PP5 co-immunoprecipitation with gp96 was strikingly reduced in post-hypoxic wild-type RTECs, suggesting that the inactivation of PP5 resulting from the dissociation of PP5 from gp96 allows the activation of ERK1/2 to occur. Inhibition of PP5 by okadaic acid, and Pp5 siRNA also restored TLR2-mediated phosphorylation of ERK1/2, and apoptosis signal-regulating kinase 1 (ASK1)/c-Jun N-terminal kinase (JNK)-mediated apoptosis in post-hypoxic Tlr2-deficient RTECs. These findings indicate that gp96 interacts with PP5 and controls TLR2-mediated induction of ERK1/2 in post-hypoxic renal tubule cells.
authors.affiliation: INSERM U773, Centre de Recherche Biomédicale Bichat-Beaujon CRB3, UFR de Médecine Xavier Bichat, Université Paris 7-Denis Diderot, Site Bichat, BP 416, F-75870 Paris Cedex 18, France.
authors.forename: Sanae Ben
authors.initials: SB
authors.lastname: Mkaddem
authors.forename: Catherine
authors.initials: C
authors.lastname: Werts
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Goujon
authors.forename: Marcelle
authors.initials: M
authors.lastname: Bens
authors.forename: Eric
authors.initials: E
authors.lastname: Pedruzzi
authors.forename: Eric
authors.initials: E
authors.lastname: Ogier-Denis
authors.forename: Alain
authors.initials: A
authors.lastname: Vandewalle
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D016227:Benzoquinones / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism*; D007674:Kidney Diseases / Q000235:genetics / Q000378:metabolism*; D007684:Kidney Tubules / Q000378:metabolism*; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D048848:MAP Kinase Kinase Kinase 5 / Q000235:genetics / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D019319:Okadaic Acid / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D015427:Reperfusion Injury / Q000235:genetics / Q000378:metabolism*; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism
chemical_list: D016227:Benzoquinones; D004791:Enzyme Inhibitors; D047029:Lactams, Macrocyclic; D008562:Membrane Glycoproteins; D009687:Nuclear Proteins; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; C053387:endoplasmin; D019319:Okadaic Acid; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048848:MAP Kinase Kinase Kinase 5; C482859:Map3k5 protein, mouse; D010749:Phosphoprotein Phosphatases; C089641:protein phosphatase 5; C001277:geldanamycin