C18-Ceramide as an essential factor in iron dependent cell death - TITLE: C18-Ceramide as an essential factor in iron dependent cell death Abstract Ferroptosis is a novel form of regulated cell death in which labile iron-dependent accumulation of phospholipid peroxides in membranes is lethal. Despite its involvement in many physiological and pathological processes, there is serious deficiency in understanding the molecular mechanisms, especially controlled by bioactive lipids, that regulate ferroptotic cell death. The long-term goal of this project is to discover the fundamental biochemical mechanisms by which the bioactive sphingolipid ceramide controls iron metabolism and ferroptosis. In preliminary studies, we found that CerS1, which specifically generates C18-ceramide, is required for ferroptosis. In addition, our preliminary results suggest that ceramide can interact with NCOA4, the adaptor protein for selective ferritin degradation in lysosomes (ferritinophagy) for labile iron generation, a key step in ferroptosis. Based on our preliminary data, we generated the novel hypothesis that CerS1-generated C18- ceramide is a crucial regulator of ferritinophagy and subsequent ferroptosis through its interaction with NCOA4, and that targeting CerS1 can mitigate ferroptosis. To test this hypothesis, we propose the following Specific Aims: Aim 1: Establish C18-ceramide as an essential factor for ferroptosis and identify the subcellular localization of the C18-ceramide pool responsible for this activity. Aim 2: Define the role of C18-ceramide–NCOA4 interaction in regulating ferritinophagy and elucidate the molecular mechanisms underlying this interaction. Aim 3: Determine the molecular mechanisms activating CerS1 in ferroptosis. Overall, these studies will establish CerS1 and C18- ceramide as key factors controlling ferroptosis via a novel lipid-protein interaction and define the biochemical basis of this control mechanism. In addition, the knowledge generated from this study will be essential for designing mechanism-based novel therapies centered around modifying ferroptosis through targeting CerS1 in diseases where ferroptosis is a central factor for pathological adverse conditions.
