Ubiquitin-like protein MNSFβ/endophilin II complex regulates Dectin-1-mediated phagocytosis and inflammatory responses in macrophages.
Post-translational modification by monoclonal nonspecific suppressor factor β (MNSFβ) has been implicated in the regulation of a variety of cellular events. Previous studies have demonstrated that MNSFβ covalently binds to the intracellular pro-apoptotic protein Bcl-G in a macrophage cell line, Raw264.7, suggesting involvement of this ubiquitin-like protein in apoptosis. Most recently, we found that MNSFβ covalently conjugates to endophilin II, a member of the endophilin A family, and inhibits phagocytosis by macrophages. In this study, we further examined the mechanism of action of MNSFβ/endophilin II complex in the phagocytosis of zymosan. MNSFβ/endophilin II I mediated inhibition of phagocytosis in Raw264.7 cells was neutralized by anti-Decti-1, β-glucan receptor, mAb, indicating that MNSFβ/endophilin II is a mediator of Dectin-1 signaling in regulating phagocytosis. The β-glucan-dependent TNFα response to zymosan was significantly increased by the treatment with endophilin II siRNA and/or MNSFβ siRNA. Conversely, cotransfection of endophilin II and MNSFβ cDNAs inhibited the enhancement of zymosan-induced TNFα production. Interestingly, endophilin II siRNA did not affect Pam3CSK4 (TLR2 specific ligand)-induced TNFα production. Endophilin II and/or MNSFβ siRNA enhanced zymosan-induced IκBα degradation. Together, these results demonstrate that MNSFβ/endophilin II inhibits the signal pathway upstream of IKK activation, but not downstream of TLR2 signaling.
Nakamura
Morihiko
M
Department of Cooperative Medical Research, Collaboration Center, Shimane University, Izumo 693-8501, Japan. nkmr0515@med.shimane-u.ac.jp
Watanabe
Natsuko
N
D000818:Animals; D002460:Cell Line; D007249:Inflammation / Q000276:immunology*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D037181:Lectins, C-Type; D008264:Macrophages / Q000276:immunology*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010587:Phagocytosis; D011499:Protein Processing, Post-Translational; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D013491:Suppressor Factors, Immunologic / Q000378:metabolism*; D000072377:Syk Kinase; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis; D025801:Ubiquitin / Q000378:metabolism*; D000099181:Dectin-1
D047908:Intracellular Signaling Peptides and Proteins; D037181:Lectins, C-Type; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011505:Protein-Tyrosine Kinases; D013491:Suppressor Factors, Immunologic; D000072377:Syk Kinase; D051195:Toll-Like Receptor 2; D014409:Tumor Necrosis Factor-alpha; D025801:Ubiquitin; D000099181:Dectin-1; C493486:Tlr2 protein, mouse; C528010:endophilin II, mouse; C072169:monoclonal nonspecific suppressor factor; C000606897:Syk protein, mouse