title: Peptide-mediated interference of TIR domain dimerization in MyD88 inhibits interleukin-1-dependent activation of NF-{kappa}B.
abstract: Myeloid differentiation factor 88 (MyD88) plays a crucial role in the signaling pathways triggered by interleukin (IL)-1 and Toll-like receptors in several steps of innate host defense. A crucial event in this signaling pathway is represented by dimerization of MyD88, which allows the recruitment of downstream kinases like IRAK-1 and IRAK-4. Herein, we have investigated the function of the Toll/IL-1 receptor (TIR) domain in MyD88 homodimerization in cell-free and in vitro experimental settings by using epta-peptides that mimic the BB-loop region of the conserved TIR domain of different proteins. By using a pull-down assay with purified glutathione S-transferase-MyD88 TIR or co-immunoprecipitation experiments, we found that epta-peptides derived from the TIR domain of MyD88 and IL-18R are the most effective in inhibiting homodimerization with either the isolated TIR or full-length MyD88. Moreover, we demonstrated that a cell permeable analog of MyD88 epta-peptide inhibits homodimerization of MyD88 TIR domains in an in vitro cell system and significantly reduces IL-1 signaling, as assayed by activation of the downstream transcription factor NF-kappaB. Our results indicate that the BB-loop in TIR domain of MyD88 is a good target for specific inhibition of MyD88-mediated signaling in vivo.
authors.affiliation: Department of Public Health and Cell Biology, University of Rome "Tor Vergata," 00173 Rome, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Loiarro
authors.forename: Claudio
authors.initials: C
authors.lastname: Sette
authors.forename: Grazia
authors.initials: G
authors.lastname: Gallo
authors.forename: Andrea
authors.initials: A
authors.lastname: Ciacci
authors.forename: Nicola
authors.initials: N
authors.lastname: Fantò
authors.forename: Domenico
authors.initials: D
authors.lastname: Mastroianni
authors.forename: Paolo
authors.initials: P
authors.lastname: Carminati
authors.forename: Vito
authors.initials: V
authors.lastname: Ruggiero
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D051943:Antennapedia Homeodomain Protein; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D007375:Interleukin-1 / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics; D008969:Molecular Sequence Data; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010455:Peptides / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000235:genetics; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D017472:Receptors, Interleukin-1 / Q000235:genetics; D016415:Sequence Alignment; D051193:Toll-Like Receptors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051943:Antennapedia Homeodomain Protein; D000943:Antigens, Differentiation; D018398:Homeodomain Proteins; D007375:Interleukin-1; D008562:Membrane Glycoproteins; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D009687:Nuclear Proteins; D010455:Peptides; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1; D051193:Toll-Like Receptors; D014157:Transcription Factors