Cytosolic phospholipase A2ε drives recycling through the clathrin-independent endocytic route

ABSTRACT Previous studies have demonstrated that membrane tubule-mediated transport events in biosynthetic and endocytic routes require phospholipase A 2 (PLA 2 ) activity. Here, we show that cytosolic phospholipase A 2 e (cPLA 2 e, also known as PLA2G4E) is targeted to the membrane compartments of the clathrin-independent endocytic route through a C-terminal stretch of positively charged amino acids, which allows the enzyme to interact with phosphoinositide lipids [especially PI(4,5)P 2 ] that are enriched in clathrin-independent endosomes. Ablation of cPLA 2 e suppressed the formation of tubular elements that carry internalized clathrin-independent cargoes, such as MHC-I, CD147 and CD55, back to the cell surface and, therefore, caused their intracellular retention. The ability of cPLA 2 e to support recycling through tubule formation relies on the catalytic activity of the enzyme, because the inactive cPLA 2 e S420A mutant was not able to recover either tubule growth or transport from clathrin-independent endosomes. Taken together, our findings indicate that cPLA 2 e is a new important regulator of trafficking processes within the clathrin-independent endocytic and recycling route. The affinity of cPLA 2 e for this pathway supports a new hypothesis that different PLA 2 enzymes use selective targeting mechanisms to regulate tubule formation locally during specific trafficking steps in the secretory and/or endocytic systems.