Macropinocytosis: a pathway to protozoan infection
Related Experiment Video
Updated: Apr 14, 2026
Measuring the pH, Redox Chemistries, and Degradative Capacity of Macropinosomes using Dual-Fluorophore Ratiometric Microscopy
Published on: August 19, 2021
Tecia M U de Carvalho1, Emile S Barrias2, Wanderley de Souza1
1Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Centro de Ciência da Saúde, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil ; Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagens e Centro Nacional de Bioimagens-CENABIO, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil.
Abstract:
Among the various endocytic mechanisms in mammalian cells, macropinocytosis involves internalization of large amounts of plasma membrane together with extracellular medium, leading to macropinosome formation. These structures are formed when plasma membrane ruffles are assembled after actin filament rearrangement. In dendritic cells, macropinocytosis has been reported to play a role in antigen presentation. Several intracellular pathogens are internalized by host cells via multiple endocytic pathways and macropinocytosis has been described as an important entry site for various organisms. Some bacteria, such as Legionella pneumophila, as well as various viruses, use this pathway to penetrate and subvert host cells. Some protozoa, which are larger than bacteria and virus, can also use this pathway to invade host cells. As macropinocytosis is characterized by the formation of large uncoated vacuoles and is triggered by various signaling pathways, which is similar to what occurs during the formation of the majority of parasitophorous vacuoles, it is believed that this phenomenon may be more widely used by parasites than is currently appreciated. Here we review protozoa host cell invasion via macropinocytosis.
Insights
Macropinocytosis, a cell-invading process, is crucial for protozoa to enter host cells. This review explores how protozoa utilize macropinocytosis for host cell invasion, highlighting its broader role than previously understood.
Area of Science:
- Cell Biology
- Infectious Diseases
- Parasitology
Background:
- Macropinocytosis is a cellular process involving the uptake of extracellular fluid and plasma membrane, forming large macropinosomes.
- This process is driven by actin rearrangements and plasma membrane ruffling, and is implicated in antigen presentation by dendritic cells.
- Various pathogens, including bacteria and viruses, utilize macropinocytosis for host cell entry and subversion.
Purpose of the Study:
- To review the role of macropinocytosis in host cell invasion by protozoa.
- To highlight the potential underappreciation of macropinocytosis as a parasitic invasion mechanism.
- To discuss the similarities between macropinocytosis and parasitophorous vacuole formation.
Main Methods:
- Literature review of studies on protozoa, host cell invasion, and macropinocytosis.
- Analysis of the mechanisms and signaling pathways involved in macropinocytosis.
- Comparison of macropinocytosis with other endocytic pathways and vacuole formation.
Main Results:
- Protozoa, despite their larger size, can effectively utilize macropinocytosis for host cell invasion.
- The characteristics of macropinocytosis, such as large vacuole formation, resemble those of parasitophorous vacuoles.
- This suggests macropinocytosis may be a more common invasion route for protozoan parasites than currently recognized.
Conclusions:
- Macropinocytosis is a significant pathway for protozoan host cell invasion.
- Further research is warranted to fully understand the extent and mechanisms of protozoan invasion via macropinocytosis.
- Recognizing macropinocytosis as a key invasion strategy can inform the development of novel anti-parasitic interventions.
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