title: Tissue factor–dependent procoagulant activity of subtilase cytotoxin, a potent AB5 toxin produced by shiga toxigenic Escherichia coli.
abstract: Subtilase cytotoxin (SubAB), produced by certain virulent Shiga toxigenic Escherichia coli strains, causes hemolytic uremic syndrome-like pathology in mice, including extensive microvascular thrombosis. SubAB acts by specifically cleaving the essential endoplasmic reticulum chaperone binding immunoglobulin protein (BiP). BiP has been reported to inhibit the activation of tissue factor (TF), the major initiator of extrinsic coagulation. We hypothesized that the apparent prothrombotic effect of SubAB in vivo may involve the stimulation of TF‐dependent procoagulant activity. TF‐dependent procoagulant activity, TF messenger RNA (mRNA) levels, and BiP cleavage were therefore examined in human macrophage cells and primary human umbilical vein endothelial cells exposed to SubAB. In both types of cells, SubAB significantly increased TF‐dependent procoagulant activity, induced TF mRNA expression, and mediated BiP cleavage. No effects were seen when cells were treated with a nonproteolytic mutant toxin, SubAA272B. Our results suggest that the procoagulant effect of SubAB may be dependent on both the up‐regulation of TF expression and the activation of TF by means of BiP cleavage.
authors.affiliation: Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: James C
authors.initials: JC
authors.lastname: Paton
authors.forename: Cheleste M
authors.initials: CM
authors.lastname: Thorpe
authors.forename: Claudine S
authors.initials: CS
authors.lastname: Bonder
authors.forename: Wai Yan
authors.initials: WY
authors.lastname: Sun
authors.forename: Adrienne W
authors.initials: AW
authors.lastname: Paton
mesh_terms: D000818:Animals; D001777:Blood Coagulation / Q000187:drug effects; D002478:Cells, Cultured; D000091342:Endoplasmic Reticulum Chaperone BiP; D042783:Endothelial Cells / Q000187:drug effects; D029968:Escherichia coli Proteins / Q000378:metabolism / Q000633:toxicity*; D020869:Gene Expression Profiling; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D054323:Shiga-Toxigenic Escherichia coli / Q000472:pathogenicity*; D013381:Subtilisins / Q000378:metabolism / Q000633:toxicity*; D013925:Thromboplastin / Q000096:biosynthesis*; D013927:Thrombosis / Q000139:chemically induced
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D013925:Thromboplastin; D013381:Subtilisins; C527234:subtilase cytotoxin, E coli