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Updated: Jun 29, 2026
11:01
Automated Imaging and Analysis for the Quantification of Fluorescently Labeled Macropinosomes
Published on: August 24, 2021
Ca2+ induces macropinocytosis via F-actin depolymerization during growth cone collapse
Hiroyuki Kabayama1, Takeshi Nakamura, Makoto Takeuchi
1Laboratory for Developmental Neurobiology, Brain Science Institute, The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. kabayama@brain.riken.jp
Molecular and Cellular Neurosciences
|October 14, 2008
Summary
Calcium release triggers macropinocytosis, a process of membrane retrieval, leading to growth cone collapse during axon guidance. This mechanism involves actin reorganization and retrograde membrane transport, inhibiting axon growth.
Area of Science:
- Neuroscience
- Cell Biology
Background:
- Growth cone collapse, a key event in repulsive axon guidance, involves a reduction in growth cone plasma membrane surface area.
- The precise mechanism driving this membrane reduction during growth cone collapse remains largely unknown.
Purpose of the Study:
- To elucidate the mechanism underlying plasma membrane reduction during growth cone collapse.
- To investigate the role of calcium release and macropinocytosis in axon guidance.
Main Methods:
- Utilized caffeine to induce calcium release from ryanodine-sensitive stores and observed its effect on growth cones.
- Investigated semaphorin 3A, a repulsive cue, for its ability to induce macropinocytosis.
- Employed jasplakinolide, an F-actin depolymerization inhibitor, to assess the role of actin cytoskeleton.
Main Results:
- Caffeine-induced calcium release triggered the formation of large vacuoles via macropinocytosis in growth cones.
- A significant correlation was found between the area of caffeine-induced macropinosomes and the extent of growth cone collapse.
- Semaphorin 3A also induced macropinocytosis, with a similar correlation observed between macropinocytic vacuole area and growth cone collapse.
- Jasplakinolide inhibited caffeine-induced macropinocytosis, highlighting the involvement of actin dynamics.
Conclusions:
- Macropinocytosis, a clathrin-independent endocytosis, is a primary mechanism for plasma membrane retrieval during growth cone collapse.
- Coordinated regulation of actin cytoskeletal reorganization and macropinocytosis-mediated retrograde membrane trafficking contributes to calcium-induced axon growth inhibition.
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