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Updated: Sep 30, 2025
High-throughput Measurement of Dictyostelium discoideum Macropinocytosis by Flow Cytometry
Published on: September 10, 2018
Oligopeptide transporter Slc15A modulates macropinocytosis in Dictyostelium by maintaining intracellular nutrient
Yiwei Zhang1,2, Hui Tu1,2, Yazhou Hao1,2
1National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
Abstract:
Macropinocytosis mediates non-selective bulk uptake of extracellular fluid. It is the major route by which axenic Dictyostelium cells obtain nutrients and has emerged as a nutrient-scavenging pathway in mammalian cells. How environmental and cellular nutrient status modulates macropinocytic activity is not well understood. By developing a high-content imaging-based genetic screen in Dictyostelium discoideum we identified Slc15A, an oligopeptide transporter located at the plasma membrane and early macropinosome, as a novel macropinocytosis regulator. We show that deletion of slc15A but not two other related slc15 genes, leads to reduced macropinocytosis, reduced cell growth and aberrantly increased autophagy in cells grown in nutrient-rich medium. Expression of Slc15A protein or supplying cells with free amino acids rescues these defects. In contrast, expression of transport-defective Slc15A or supplying cells with amino acids in their di-peptide forms fails to rescue these defects. Therefore, Slc15A modulates the level of macropinocytosis by maintaining the intracellular availability of key amino acids through extraction of oligopeptides from the early macropinocytic pathway. We propose that Slc15A constitutes part of a positive feedback mechanism coupling cellular nutrient status and macropinocytosis. This article has an associated First Person interview with the first authors of the paper.
Insights
The oligopeptide transporter Slc15A regulates macropinocytosis in Dictyostelium cells by ensuring amino acid availability. Deleting slc15A impairs nutrient uptake and cell growth, highlighting its role in nutrient sensing.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Macropinocytosis is a key process for non-selective bulk uptake of extracellular fluid and nutrients.
- The regulation of macropinocytosis by environmental and cellular nutrient status is not fully understood.
- Dictyostelium discoideum serves as a model organism for studying nutrient acquisition pathways.
Purpose of the Study:
- To identify novel regulators of macropinocytosis in Dictyostelium.
- To elucidate the mechanism by which nutrient status influences macropinocytic activity.
- To investigate the role of oligopeptide transporters in nutrient scavenging.
Main Methods:
- High-content imaging-based genetic screen in Dictyostelium discoideum.
- Gene deletion and expression studies of Slc15A and related transporters.
- Analysis of macropinocytosis, cell growth, and autophagy levels.
- Functional assays with free amino acids and di-peptides.
Main Results:
- Slc15A, an oligopeptide transporter, was identified as a novel regulator of macropinocytosis.
- Deletion of slc15A reduced macropinocytosis, cell growth, and increased autophagy in nutrient-rich conditions.
- Restoration of Slc15A function or supply of free amino acids rescued these defects.
- Transport-defective Slc15A or di-peptide supply failed to rescue the observed phenotypes.
Conclusions:
- Slc15A modulates macropinocytosis by extracting oligopeptides to maintain intracellular amino acid levels.
- Slc15A acts as a positive feedback mechanism linking cellular nutrient status to macropinocytosis.
- This study reveals a novel link between amino acid transport and bulk fluid uptake.
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