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MiR-146a activates WAVE2 expression and enhances phagocytosis in lipopolysaccharide-stimulated RAW264.7 macrophages
Zhongwei Cao1, Qunyan Yao1, Shuncai Zhang1
1Department of Gastroenterology, Zhongshan Hospital, Fudan University Shanghai, China.
Abstract:
MiR-146a has been shown to play a critical role in cell immunity and phagocytosis, processes that require rearrangement of the cytoskeleton. However, the detailed mechanism by which miR-146a regulates these events remains elusive. Here, we used luciferase reporter and protein assays to show that the cytoskeleton-regulatingprotein verprolin-homologous protein 2 (WAVE2), is a direct target of miR-146a. MiR-146a overexpression resulted in a decrease in WAVE2 protein expression under endotoxin-free culture conditions. Unexpectedly, however, miR-146a activated rather than repressed the expression of WAVE2 in macrophage RAW264.7 cells when cultured continuously in the presence of endotoxin. Furthermore, we demonstrated that miR-146a induced WAVE2 expression and enhanced phagocytosis in lipopolysaccharide-stimulated RAW264.7 macrophages. Our study suggests that lipopolysaccharide- induced miR146a indirectly activates WAVE2 expression; thus, facilitating cytoskeletal reorganization and phagocytosis in lipopolysaccharide-stimulated macrophages.
Insights
MicroRNA-146a (miR-146a) regulates phagocytosis by influencing WAVE2 protein expression. Lipopolysaccharide stimulation activates miR-146a, indirectly boosting WAVE2 and enhancing macrophage phagocytic activity.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- MicroRNA-146a (miR-146a) is crucial for immune responses and phagocytosis.
- Cytoskeletal rearrangement is essential for these processes.
- The precise mechanism of miR-146a's regulation of the cytoskeleton was unclear.
Purpose of the Study:
- To elucidate the mechanism by which miR-146a regulates cytoskeletal dynamics.
- To identify direct targets of miR-146a involved in these processes.
- To investigate the role of miR-146a in lipopolysaccharide (LPS)-stimulated macrophages.
Main Methods:
- Luciferase reporter assays to confirm direct targeting.
- Protein assays to measure WAVE2 expression levels.
- Cell culture of RAW264.7 macrophages under varying conditions (endotoxin-free vs. continuous endotoxin exposure).
Main Results:
- Verprolin-homologous protein 2 (WAVE2) was identified as a direct target of miR-146a.
- MiR-146a overexpression decreased WAVE2 in endotoxin-free conditions.
- Unexpectedly, miR-146a activated WAVE2 in LPS-stimulated RAW264.7 cells, enhancing phagocytosis.
Conclusions:
- LPS-induced miR-146a indirectly activates WAVE2 expression.
- This activation facilitates cytoskeletal reorganization.
- The miR-146a-WAVE2 axis enhances phagocytosis in LPS-stimulated macrophages.
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