Pharmacologic properties of P2Z/P2X7receptor characterized in murine dendritic cells: role on the induction of apoptosis

Abstract

In the immune system, extracellular adenosine 5′-triphosphate (ATP) mediates a variety of effects mainly through activation of a particular receptor subtype, the pore-forming P2Z/P2X7 purinoceptor. This purinergic receptor has been described chiefly in cells of hemopoietic origin such as T cells, thymocytes, monocytes, macrophages, and phagocytic cells of thymic reticulum. In this study, we characterized the P2Z/P2X7 purinoceptor and the ATP-mediated apoptosis in murine spleen–derived dendritic cells (DCs). Dye uptake and apoptosis were evaluated by flow cytometry. ATP-treated DCs were permeable to different low-molecular-weight fluorescent probes such as ethidium bromide, YO-PRO 1, and lucifer yellow. Such an effect was dose-dependent (EC50: 721 μmol/L); mediated by the fully anionic agonist (ATP4−); and specifically stimulated by ATP, BzATP, and ATPγS. Additionally, an ATP-induced increase in intracellular calcium was detected by microfluorometry. Furthermore, ATP treatment induced a significant increase in apoptotic DCs (64.46% ± 3.8%) when compared with untreated control cells (34% ± 5.8%), as ascertained by the TdT-mediated dUTP nick end labeling technique. Both ATP-induced DC permeabilization and apoptosis were inhibited by oxidized ATP, a P2Z/P2X7-specific antagonist. In conclusion, we characterized the expression of the P2Z/P2X7purinoceptor in murine spleen–derived DCs and described its role on the induction of apoptosis.