dictyNews
Electronic Edition
Volume 47, number 24
December 3, 2021

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Abstracts
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The Dynamics of Aerotaxis in a Simple Eukaryotic Model

Marta Biondo, Cristina Panuzzo, Shahzad M. Ali, Salvatore Bozzaro, 
Matteo Osella, Enrico Bracco and Barbara Pergolizzi

Front. Cell Dev. Biol., 23 November 2021 
https://doi.org/10.3389/fcell.2021.720623


Dictyostelium: A Tractable Cell and Developmental Model in 
Biomedical Research.

In aerobic organisms, oxygen is essential for efficient energy 
production, and it acts as the last acceptor of the mitochondrial 
electron transport chain and as regulator of gene expression. 
However, excessive oxygen can lead to production of deleterious 
reactive oxygen species. Therefore, the directed migration of single 
cells or cell clumps from hypoxic areas toward a region of optimal 
oxygen concentration, named aerotaxis, can be considered an 
adaptive mechanism that plays a major role in biological and 
pathological processes. One relevant example is the development 
of O2 gradients when tumors grow beyond their vascular supply, 
leading frequently to metastasis. In higher eukaryotic organisms, 
aerotaxis has only recently begun to be explored, but genetically 
amenable model organisms suitable to dissect this process remain 
an unmet need. In this regard, we sought to assess whether 
Dictyostelium cells, which are an established model for chemotaxis 
and other motility processes, could sense oxygen gradients and 
move directionally in their response. By assessing different physical 
parameters, our findings indicate that both growing and starving 
Dictyostelium cells under hypoxic conditions migrate directionally 
toward regions of higher O2 concentration. This migration is 
characterized by a specific pattern of cell arrangement. A thickened 
circular front of high cell density (corona) forms in the cell cluster 
and persistently moves following the oxygen gradient. Cells in the 
colony center, where hypoxia is more severe, are less motile and 
display a rounded shape. Aggregation-competent cells forming 
streams by chemotaxis, when confined under hypoxic conditions, 
undergo stream or aggregate fragmentation, giving rise to multiple 
small loose aggregates that coordinately move toward regions of 
higher O2 concentration. By testing a panel of mutants defective in 
chemotactic signaling, and a catalase-deficient strain, we found that 
the latter and the pkbR1null exhibited altered migration patterns. Our 
results suggest that in Dictyostelium, like in mammalian cells, an 
intracellular accumulation of hydrogen peroxide favors the migration 
toward optimal oxygen concentration. Furthermore, differently from 
chemotaxis, this oxygen-driven migration is a G protein-independent 
process.

 
Submitted by Barbara Pergolizzi [[log in to unmask]]
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