Phospholipase D1: a key factor for the exocytotic machinery in neuroendocrine cells

Abstract

Phospholipase D (PLD) has been proposed to mediate cytoskeletal remodeling and vesicular trafficking along the secretory pathway. We recently described the activation of an ADP ribosylation factor‐regulated PLD at the plasma membrane of chromaffin cells undergoing secretagogue‐stimulated exocytosis. We show here that the isoform involved is PLD1b, and, using a real‐time assay for individual cells, that PLD activation and exocytosis are closely correlated. Moreover, overexpressed PLD1, but not PLD2, increases stimulated exocytosis in a phosphatidylinositol 4,5‐bisphosphate‐dependent manner, whereas catalytically inactive PLD1 inhibits it. These results provide the first direct evidence that PLD1 is an important component of the exocytotic machinery in neuroendocrine cells.