Regulation of phototransduction responsiveness and retinal degeneration by a phospholipase D-generated signaling lipid

Abstract

Drosophila melanogaster phototransduction proceeds via a phospholipase C (PLC)-triggered cascade of phosphatidylinositol (PI) lipid modifications, many steps of which remain undefined. We describe the involvement of the lipid phosphatidic acid and the enzyme that generates it, phospholipase D (Pld), in this process. Pldnull flies exhibit decreased light sensitivity as well as a heightened susceptibility to retinal degeneration. Pld overexpression rescues flies lacking PLC from light-induced, metarhodopsin-mediated degeneration and restores visual signaling in flies lacking the Pl transfer protein, which is a key player in the replenishment of the Pl 4,5-bisphosphate (PlP2) substrate used by PLC to transduce light stimuli into neurological signals. Altogether, these findings suggest that Pld facilitates phototransduction by maintaining adequate levels of PlP2 and by protecting the visual system from metarhodopsin-induced, low light degeneration. © The Rockefeller University Press.