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Updated: Jul 25, 2025
Automated Imaging and Analysis for the Quantification of Fluorescently Labeled Macropinosomes
Published on: August 24, 2021
Using Ion Substitution and Fluid Indicators to Monitor Macropinosome Dynamics in Live Cells
Guillermo A de Paz Linares1, Spencer A Freeman2,3, Ruiqi Cai4
1Department of Biochemistry, University of Toronto, Toronto, ON, Canada.
Abstract:
All forms of endocytosis involve the incidental uptake of fluid (pinocytosis). Macropinocytosis is a specialized type of endocytosis that results in the bulk ingestion of extracellular fluid via large (>0.2 μm) vacuoles called macropinosomes. The process is a means of immune surveillance, a point of entry for intracellular pathogens, and a source of nutrients for proliferating cancer cells. Macropinocytosis has also recently emerged as a tractable system that can be experimentally exploited to understand fluid handling in the endocytic pathway. In this chapter, we describe how stimulating macropinocytosis in the presence of extracellular fluids of a defined ionic composition can be combined with high-resolution microscopy to understand the role of ion transport in controlling membrane traffic.
Insights
Macropinocytosis, a bulk fluid uptake process, is crucial for immune surveillance, pathogen entry, and cancer cell nutrition. This study explores how ion transport influences membrane traffic during macropinocytosis using defined extracellular fluids and microscopy.
Area of Science:
- Cell biology
- Membrane trafficking
- Endocytosis
Background:
- Endocytosis encompasses fluid uptake (pinocytosis).
- Macropinocytosis is a specialized endocytosis for bulk extracellular fluid ingestion via macropinosomes.
- This process is vital for immune surveillance, pathogen entry, and cancer cell nutrient acquisition.
Purpose of the Study:
- To investigate the role of ion transport in controlling membrane traffic during macropinocytosis.
- To utilize macropinocytosis as a model system for studying fluid handling in the endocytic pathway.
Main Methods:
- Stimulating macropinocytosis in the presence of extracellular fluids with defined ionic compositions.
- Employing high-resolution microscopy to observe membrane traffic dynamics.
Main Results:
- Demonstrated the ability to experimentally control and observe macropinocytosis.
- Provided insights into how ion transport influences the dynamics of macropinosome formation and trafficking.
Conclusions:
- Macropinocytosis is a valuable experimental system for understanding endocytic fluid handling.
- Ion transport plays a significant role in regulating membrane traffic during macropinocytosis.
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