P2X7 receptors are non-selective cation channels gated by extracellular ATP. Prolonged stimulation of the P2X7 receptor leads to an increase in cell permeability, cytokine release and apoptosis/necrosis. Application of PIP2 to inside-out patches strongly activated all homomeric members of the P2X receptor family, including P2X7 channels. Blockade of PIP2 re-synthesis or induction of PIP 2 hydrolysis diminished ATP-gated P2X7 currents. Several positively charged residues in the proximal C-terminus of P2X7 were found to be important for PIP2 interactions, as mutation of these sites reduced the apparent affinity for PIP2 and enhanced current inhibition by PIP2 depletion. In addition, we demonstrated the dependence of ATP-mediated cell death on P2X7 receptor interaction with PIP2 in three different cell systems: HEK cells stably transfected with P2X7, primary T cells and a macrophage cell line. These results identify PIP2 as a critical regulator of the function of the extracellular ligand-gated P2X receptor/channels and provide a novel way to control ATP-mediated cell death.
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