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Updated: Jul 2, 2026
08:05
Visualizing Membrane Ruffle Formation using Scanning Electron Microscopy
Published on: May 27, 2021
Membrane ruffles capture C3bi-opsonized particles in activated macrophages
Prerna C Patel1, Rene E Harrison
1Departments of Biological Sciences and Cell and Systems Biology, University of Toronto Scarborough, Toronto, ON, M1C 1A4, Canada.
Molecular Biology of the Cell
|September 5, 2008
Summary
Macrophages use dynamic membrane ruffles, part of macropinocytosis machinery, to capture C3bi-opsonized particles via Mac-1. This process requires cytoskeletal elements and intracellular membrane transport for effective phagocytosis.
Area of Science:
- Immunology
- Cell Biology
- Macrophage Biology
Background:
- FcgammaR-mediated phagocytosis uses pseudopods, while Mac-1-mediated phagocytosis was thought to lack elaborate membrane structures.
- Understanding Mac-1-mediated particle uptake mechanisms is crucial for immune cell function.
Purpose of the Study:
- To investigate the mechanism of C3bi-opsonized particle binding during Mac-1-mediated phagocytosis.
- To identify the role of membrane structures and intracellular components in this process.
Main Methods:
- Utilized PMA- and LPS-stimulated macrophages.
- Employed Total Internal Reflection Fluorescence (TIRF) imaging.
- Investigated the role of F-actin, microtubules (MTs), kinesin, Rab11, and CLIP-170.
Main Results:
- Dynamic membrane ruffles, components of macropinocytosis machinery, facilitate C3bi-particle binding.
- High-affinity Mac-1 and talin enrich in these ruffles.
- Cytoskeleton (F-actin, MTs) and MT motor kinesin are essential for ruffle formation and Mac-1 expression.
- Rab11-positive vesicles and CLIP-170 colocalize at particle adherence sites, with Rab11 influencing ruffle formation and particle binding.
Conclusions:
- A novel membrane ruffle "capture" mechanism for C3bi-particle binding during Mac-1-mediated phagocytosis was identified.
- Established a functional link between integrin activation, macropinocytosis, and phagocytosis in macrophages.
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