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Updated: Jun 8, 2026

Mesenchymal Stem Cell Regulation of Macrophage Phagocytosis; Quantitation and Imaging
Published on: July 16, 2021
Ubiquitin-like protein MNSFβ/endophilin II complex regulates Dectin-1-mediated phagocytosis and inflammatory
Morihiko Nakamura1, Natsuko Watanabe
1Department of Cooperative Medical Research, Collaboration Center, Shimane University, Izumo 693-8501, Japan. nkmr0515@med.shimane-u.ac.jp
Abstract:
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.
Insights
Monoclonal nonspecific suppressor factor β (MNSFβ) and endophilin II regulate macrophage phagocytosis via Dectin-1 signaling. Silencing these proteins enhances zymosan-induced TNFα production and IκBα degradation.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Post-translational modification by MNSFβ regulates cellular events.
- MNSFβ conjugates to Bcl-G, impacting apoptosis.
- MNSFβ also conjugates to endophilin II, inhibiting macrophage phagocytosis.
Purpose of the Study:
- To investigate the mechanism of MNSFβ/endophilin II complex in zymosan phagocytosis.
- To elucidate the role of MNSFβ/endophilin II in Dectin-1 signaling and TNFα production.
Main Methods:
- Utilized Raw264.7 macrophage cell line.
- Employed siRNA to silence endophilin II and MNSFβ.
- Analyzed TNFα production and IκBα degradation in response to zymosan and Pam3CSK4.
- Used anti-Dectin-1 mAb to assess Dectin-1 signaling involvement.
Main Results:
- MNSFβ/endophilin II inhibition of phagocytosis is mediated by Dectin-1 signaling.
- Silencing MNSFβ or endophilin II enhanced zymosan-induced TNFα production.
- Silencing MNSFβ or endophilin II enhanced zymosan-induced IκBα degradation.
- MNSFβ/endophilin II complex acts upstream of IKK activation, independent of TLR2 signaling.
Conclusions:
- MNSFβ/endophilin II complex is a key regulator of Dectin-1-mediated phagocytosis and inflammatory responses.
- The MNSFβ/endophilin II complex inhibits signaling pathways upstream of IKK activation.
- This complex plays a crucial role in modulating macrophage responses to fungal components like zymosan.
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