A molecular pathway for light-dependent photoreceptor apoptosis in Drosophila

Light-induced photoreceptor apoptosis occurs in many forms of inherited ret inal degeneration resulting in blindness in both vertebrates and invertebra tes. Though mutations in several photoreceptor signaling proteins have been implicated in triggering this process, the molecular events relating light activation of rhodopsin to photoreceptor death are yet unclear. Here, we u ncover a pathway by which activation of rhodopsin in Drosophila mediates ap optosis through a G protein-independent mechanism. This process involves th e formation of membrane complexes of phosphorylated, activated rhodopsin an d its inhibitory protein arrestin, and subsequent clathrin-dependent endocy tosis of these complexes into a cytoplasmic compartment Together, these dat a define the proapoptotic molecules in Drosophila photoreceptors and indica te a novel signaling pathway for light-activated rhodopsin molecules in con trol of photoreceptor viability.