title: X-box binding protein 1 (XBP1s) is a critical determinant of Pseudomonas aeruginosa homoserine lactone-mediated apoptosis.
abstract: Pseudomonas aeruginosa infections are associated with high mortality rates and occur in diverse conditions including pneumonias, cystic fibrosis and neutropenia. Quorum sensing, mediated by small molecules including N-(3-oxo-dodecanoyl) homoserine lactone (C12), regulates P. aeruginosa growth and virulence. In addition, host cell recognition of C12 initiates multiple signalling responses including cell death. To gain insight into mechanisms of C12-mediated cytotoxicity, we studied the role of endoplasmic reticulum stress in host cell responses to C12. Dramatic protection against C12-mediated cell death was observed in cells that do not produce the X-box binding protein 1 transcription factor (XBP1s). The leucine zipper and transcriptional activation motifs of XBP1s were sufficient to restore C12-induced caspase activation in XBP1s-deficient cells, although this polypeptide was not transcriptionally active. The XBP1s polypeptide also regulated caspase activation in cells stimulated with N-(3-oxo-tetradecanoyl) homoserine lactone (C14), produced by Yersinia enterolitica and Burkholderia pseudomallei, and enhanced homoserine lactone-mediated caspase activation in the presence of endogenous XBP1s. In C12-tolerant cells, responses to C12 including phosphorylation of p38 MAPK and eukaryotic initiation factor 2α were conserved, suggesting that C12 cytotoxicity is not heavily dependent on these pathways. In summary, this study reveals a novel and unconventional role for XBP1s in regulating host cell cytotoxic responses to bacterial acyl homoserine lactones.
authors.affiliation: Department of Nephrology, University of California, San Francisco, San Francisco, California, United States of America.
authors.forename: Cathleen D
authors.initials: CD
authors.lastname: Valentine
authors.forename: Marc O
authors.initials: MO
authors.lastname: Anderson
authors.forename: Feroz R
authors.initials: FR
authors.lastname: Papa
authors.forename: Peter M
authors.initials: PM
authors.lastname: Haggie
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D003603:Cytotoxins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D059865:Endoplasmic Reticulum Stress; D004789:Enzyme Activation / Q000235:genetics; D015852:Eukaryotic Initiation Factor-2 / Q000235:genetics / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D000071717:X-Box Binding Protein 1; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D003603:Cytotoxins; D004268:DNA-Binding Proteins; D015852:Eukaryotic Initiation Factor-2; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605544:Xbp1 protein, mouse; C088386:homoserine lactone; D048051:p38 Mitogen-Activated Protein Kinases; D020169:Caspases; D015107:4-Butyrolactone