NADPH-oxidase-derived ROS alterscell migration by modulating adhesions dynamics.

Abstract

Cell migration requires the coordinated activation of structural and signalling molecules, such as the RhoGTPase Rac1. It is known that the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex assembly, which generates reactive oxygen species (ROS) at the cell membrane, also relies on Rac1 activation, indicating a possible effect of ROS during cell migration. In this study, we evaluated the effect of NADPH-oxidase-derived ROS on the migration process. Using time-lapse videos of CHO.K1 cells plated on fibronectin (2μg/ml) or collagen (5μg/cm2 ), we observed that depletion of ROS by N-acetyl-cysteine (NAC, 10mM), an unspecific antioxidant, or diphenyliodonium (DPI, 10μM), a NADPH-oxidase inhibitor, induced a ∼50% decrease in migration speed and severely impacted migration directionality. Then, we analysed the effects of NADPH oxidase on three migratory events: protrusion rate, adhesion process and signalling pathways related to cell migration. DPI induced an increase of ∼3 protrusion/cell, which were 2× faster but had a ∼50% retraction when compared with control. By pull-down assay, we observed no changes on Rac1 activation, indicating that ROS-mediated effects were related to downstream molecules, such as adhesion-related molecules. A reduction of the adhesion marker FAK-Y397 levels in cells treated with NAC and DPI was observed. In order to analyse adhesion dynamics, CHO.K1 cells transfected with paxillin-GFP analysed with total internal reflectance fluorescence (TIRF) indicated that DPI (5μM) induced larger adhesions when compared with control. These results indicate that the local generation of NADPH-oxidase-derived ROS can modulate cell migration due to changes on adhesion dynamics and signalling. This study highlights the physiological requirement of ROS for cell migration and the potential use of these molecules as targets to modulate the cell migration process at different diseases.