Enhancement of ATP-induced Currents by Phospholipase D1 Overexpressed in PC12 Cells

Enhancement of ATP-induced Currents by Phospholipase D1 Overexpressed in PC12 Cells

Using phospholipase D1 (PLD1)-overexpressing PC12 (PLD1-PC12) cells, the regulatory roles of PLD1 on ATP-induced currents were investigated. In control and PLD1-PC12 cells, ATP increased PLD activity in an external Ca<SUP>2&#8290;</SUP> dependent manner. PLD activity stimulated by ATP was substantially larger in PLD1-PC12 cells than in control cells. In whole-cell voltage-clamp mode, ATP induced transient inward and outward currents. The outward currents inhibited by TEA or charybdotoxin were significantly larger in PLD1-PC12 cells than in control cells. The inward currents known as Ca<SUP>2&#8290;</SUP> permeable nonselective cation currents were also larger in PLD1-PC12 cells than in control cells. However, the difference between the two groups of cells disappeared in Ca<SUP>2&#8290;</SUP>-free external solution, where ATP did not activate PLD. Finally, ATP-induced <SUP>45</SUP>Ca uptakes were also larger in PLD1-PC12 cells than in control cells. These results suggest that PLD enhances ATP-induced Ca<SUP>2&#8290;</SUP> influx via Ca<SUP>2&#8290;</SUP> permeable nonselective cation channels and increases subsequent Ca<SUP>2&#8290;</SUP>-activated K<SUP>&#8290;</SUP> currents in PC12 cells.