title: Transglutaminase-catalyzed incorporation of polyamines masks the DNA-binding region of the transcription factor Relish.
abstract: InDrosophila, the final immune deficiency (IMD) pathway-dependent signal is transmitted through proteolytic conversion of the nuclear factor-κB (NF-κB)-like transcription factor Relish to the active N-terminal fragment Relish-N. Relish-N is then translocated from the cytosol into the nucleus for the expression of IMD-controlled genes. We previously demonstrated that transglutaminase (TG) suppresses the IMD pathway by polymerizing Relish-N to inhibit its nuclear translocation. Conversely, we also demonstrated that orally ingested synthetic amines, such as monodansylcadaverine (DCA) and biotin-labeled pentylamine, are TG-dependently incorporated into Relish-N, causing the nuclear translocation of modified Relish-N in gut epithelial cells. It remains unclear, however, whether polyamine-containing Relish-N retains transcriptional activity. Here, we used mass spectrometry analysis of a recombinant Relish-N modified with DCA by TG activity after proteolytic digestion and show that the DCA-modified Gln residues are located in the DNA-binding region of Relish-N. TG-catalyzed DCA incorporation inhibited binding of Relish-N to the Rel-responsive element in the NF-κB-binding DNA sequence. Subcellular fractionation of TG-expressingDrosophilaS2 cells indicated that TG was localized in both the cytosol and nucleus. Of note, natural polyamines, including spermidine and spermine, competitively inhibited TG-dependent DCA incorporation into Relish-N. Moreover,in vivoexperiments demonstrated that Relish-N was modified by spermine and that this modification reduced transcription of IMD pathway-controlledcecropin A1anddiptericingenes. These findings suggest that intracellular TG regulates Relish-N-mediated transcriptional activity by incorporating polyamines into Relish-N and via protein-protein cross-linking.
authors.affiliation: From the Graduate School of Systems Life Sciences.
authors.forename: Kouki
authors.initials: K
authors.lastname: Maki
authors.affiliation: Institute for Advanced Study, and.|Department of Biology, Faculty of Science, Kyushu University, Fukuoka 819-0395, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Shibata
authors.affiliation: From the Graduate School of Systems Life Sciences, skawascb@kyudai.jp.|Department of Biology, Faculty of Science, Kyushu University, Fukuoka 819-0395, Japan.
authors.forename: Shun-Ichiro
authors.initials: SI
authors.lastname: Kawabata
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis / Q000235:genetics; D002103:Cadaverine / Q000031:analogs & derivatives* / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D029721:Drosophila Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000166:cytology; D000072417:Protein Domains; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D011503:Transglutaminases / Q000235:genetics / Q000378:metabolism*
chemical_list: D023181:Antimicrobial Cationic Peptides; C432783:DptB protein, Drosophila; D029721:Drosophila Proteins; C101626:Rel protein, Drosophila; D014157:Transcription Factors; C031161:cecropin A; D011503:Transglutaminases; C008542:monodansylcadaverine; D002103:Cadaverine
keywords: DNA-binding protein; Drosophila; NF-κB transcription factor; enzyme; innate immunity; polyamine; protein cross-linking; transglutaminase