Evidence for P-Glycoprotein Involvement in Cell Volume Regulation Using Coulter Sizing in Flow Cytometry

International audienceThe regulation of cell volume is an essential function that is coupled to a varietyof physiological processes such as receptor recycling, excitability and contraction,cell proliferation, migration, and programmed cell death. Under stress, cells undergoemergency swelling and respond to such a phenomenon with a regulatory volume decrease(RVD) where they release cellular ions, and other osmolytes as well as a concomitant lossof water. The link between P-glycoprotein, a transmembrane transporter, and cell volumeregulation is controversial, and changes in cells volume are measured using microscopy orelectrophysiology. For instance, by using the patch-clamp method, our team demonstratedthat chloride currents activated in the RVD were more intense and rapid in a breast cancercell line overexpressing the P-glycoprotein (P-gp). The Cell Lab Quanta SC is a flowcytometry system that simultaneously measures electronic volume, side scatter and threefluorescent colors; altogether this provides unsurpassed population resolution and accuratecell counting. Therefore, here we propose a novel method to follow cellular volume. Byusing the Coulter-type channel of the cytometer Cell Lab Quanta SC MPL (multi-platformloading), we demonstrated a role for the P-gp during different osmotic treatments, but alsoa differential activity of the P-gp through the cell cycle. Altogether, our data stronglysuggests a role of P-gp in cell volume regulation