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Involvement of Annexin A2 in Serum-MAF Dependent Phagocytic Activation of Macrophages
Kumpei Kawakatsu1, Misato Maemura1, Yoshika Seta1
1Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Japan.
Background/Aim:
Serum-derived macrophage activating factor (serum-MAF) is expected to have adjuvant effects through rapid phagocytic activation, which depends on F-actin accumulation in multi-layered membrane ruffles induced within 5 min after serum-MAF addition. This study aimed to elucidate the importance of annexin A2, which is a multifunctional Ca2+-binding protein related to cytoskeletal membrane dynamics, in serum-MAF signalling.
Materials And Methods:
Annexin A2 and F-actin localizations were analyzed via immunostaining and confocal microscopy. Using EGTA as chelator, the role of Ca2+ in serum-MAF signalling was examined.
Results:
Annexin A2 was found to translocate from the cytosol to the cell cortex within 30 s of serum-MAF stimulation. Ca2+ chelation inhibited the translocation of annexin A2, frill-like structure formation, and phagocytic activation by serum-MAF.
Conclusion:
Annexin A2 and Ca2+ were responsible for the rapid phagocytic activation by serum-MAF. This study provides an understanding of phagocytic activation in macrophages, which could be beneficial for cancer immunotherapy.
Insights
Serum-derived macrophage activating factor (serum-MAF) rapidly activates phagocytosis via annexin A2 and calcium ions. This process involves annexin A2 translocation and F-actin accumulation, crucial for macrophage function.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Serum-derived macrophage activating factor (serum-MAF) is known to induce rapid phagocytic activation.
- This activation is dependent on F-actin accumulation within 5 minutes of serum-MAF addition.
- Annexin A2, a calcium-binding protein, is implicated in cytoskeletal dynamics.
Purpose of the Study:
- To investigate the role of annexin A2 in serum-MAF-mediated signaling.
- To elucidate the mechanism of rapid phagocytic activation in macrophages.
Main Methods:
- Immunostaining and confocal microscopy were used to analyze annexin A2 and F-actin localization.
- Calcium (Ca2+) chelation with EGTA was employed to assess the role of calcium in the signaling pathway.
Main Results:
- Annexin A2 translocated from the cytosol to the cell cortex within 30 seconds of serum-MAF stimulation.
- Calcium chelation inhibited annexin A2 translocation, frill-like structure formation, and subsequent phagocytic activation.
- These findings highlight the critical involvement of annexin A2 and calcium in the early stages of serum-MAF signaling.
Conclusions:
- Annexin A2 and calcium ions are essential for the rapid phagocytic activation induced by serum-MAF.
- Understanding this pathway provides insights into macrophage activation mechanisms.
- This knowledge may contribute to the development of novel cancer immunotherapies.
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