title: Serpin 2a is induced in activated macrophages and conjugates to a ubiquitin homolog.
abstract: After i.p. infection of mice with the intracellular bacterium Mycobacterium bovis bacillus Calmette-Guérin, macrophages recovered from the peritoneal cavity display classical signs of immune activation. We have identified a member of the serine protease inhibitor (serpin) family which is highly induced in macrophages during bacillus Calmette-Guérin infection. Serpin 2a (spi2a) expression is also induced in macrophages in vivo during infection with Salmonella typhimurium and Listeria monocytogenes, and in vitro by a variety of bacteria and bacterial products. The cytokine IFN-gamma also induces spi2a expression in macrophages, and this induction is synergistic with bacterial products. We also demonstrate here that a ubiquitin homolog, IFN-stimulated gene of 15-kDa (ISG15), is strongly induced during in vitro and in vivo activation of macrophages and that it conjugates to spi2a in activated macrophages. The ISG15-spi2a conjugates were identified by tandem mass spectrometry and contained spi2a conjugated to either one or two molecules of ISG15. Whereas spi2a was induced by either bacterial products or IFN-gamma, ISG15 was induced only by bacterial products. Although many protein targets have been described for ubiquitin conjugation, spi2a is the first ISG15-modified protein to be reported. Macrophage activation is accompanied by the activation of a variety of proteases. It is of interest that a member of the serine protease inhibitor family is concomitantly induced and modified by a ubiquitin-like protein.
authors.affiliation: Department of Immunology, University of Washington, Seattle, WA 98185, USA. jah@itsa.ucsf.edu
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Hamerman
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Hayashi
authors.forename: Lea A
authors.initials: LA
authors.lastname: Schroeder
authors.forename: Steven P
authors.initials: SP
authors.lastname: Gygi
authors.forename: Arthur L
authors.initials: AL
authors.lastname: Haas
authors.forename: Lynne
authors.initials: L
authors.lastname: Hampson
authors.forename: Paul
authors.initials: P
authors.lastname: Coughlin
authors.forename: Ruedi
authors.initials: R
authors.lastname: Aebersold
authors.forename: Alan
authors.initials: A
authors.lastname: Aderem
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001424:Bacterial Infections / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism*; D007371:Interferon-gamma / Q000494:pharmacology; D046911:Macromolecular Substances; D008262:Macrophage Activation; D008264:Macrophages / Q000187:drug effects / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D011135:Polysaccharides, Bacterial / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D015843:Serpins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D025801:Ubiquitin / Q000235:genetics; D014452:Ubiquitins; D015854:Up-Regulation
chemical_list: D016207:Cytokines; C489550:G1p2 protein, mouse; D046911:Macromolecular Substances; D011135:Polysaccharides, Bacterial; D012333:RNA, Messenger; C490400:Serpina3k protein, mouse; D015843:Serpins; D025801:Ubiquitin; D014452:Ubiquitins; D007371:Interferon-gamma