"Aerotaxis, a new way to cope with hypoxia. Results and perspectives"
Philippe Gonzalo and Ivan Mikaelian
Oxygen gradients are widespread in the body and in the developing embryo. Indeed, among all of the nutrients carried by the bloodstream to cells, oxygen is the most limiting, leading cells to rely on glycolysis for ATP production instead of the highly efficient oxidative phosphorylation process. In tissues, depending on oxygen supply and on intensity of cell metabolism, oxygen concentrations drop from 80-100 mmHg (103-129 µmol/L) in arteriolar blood to about 24 mmHg (31 µmol/L) in the most efficiently perfused organs and to ≤1% (9 µmol/L) in the most hypoxic ones. These gradients fluctuate over short distances (tens of micrometres). Hence, adjacent cells within the same tissue are exposed to very different oxygen concentrations and must therefore display very different metabolic properties.
Aerotaxis, the chemotactism to oxygen, is well documented in prokaryotes. We reported for the first time that nontumorigenic breast epithelial human cells also display unequivocal directional migration towards oxygen in steep oxygen gradients [1]). In this seminar, we will expose the main experiments that led to the discovery of the molecular characteristics of aerotaxis in breast epithelial cells. Rather than adapting to hypoxia, aerotaxis involves moving to oxygen, which is seemingly an ancient and common feature of eukaryotic respiring cells since we were able to establish its presence in the Dyctostelium discoidium social amoeba (Cochet-Escartin et al., 2021). Since hypoxia is an recognized feature of cancers and hypoxia has been linked to increased rate of metastasis, the putative role of aerotaxis in the swarming cancer cells in the body using oxygen as an escape signal was interesting. The results of aerotaxis tests on freshly isolated primary cells from all of the most common breast tumour types and their putative application will also be presented.