Characterizing the Regulation of Ferroptosis

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Project Summary/Abstract Ferroptosis is a non-apoptotic cell death process that can suppress tumor formation and contribute to disease pathology. The long-term objective of this research is to understand the molecular regulation of ferroptosis. Ferroptosis is thought to occur through a stereotypical and invariant lipid-dependent mechanism. However, in new preliminary studies we have uncovered evidence for two different forms of ferroptosis defined by unique genetic regulation and metabolic alterations. We find that ferroptosis triggered by direct inactivation of the enzyme GPX4 requires the function of the lipid metabolic enzyme ACSL4. A second sub-type of ferroptosis, triggered by cystine deprivation, does not require ACSL4 or related lipid metabolic enzymes and instead relies on a novel set of genes. Guided by these new preliminary data, our central hypothesis is that ferroptosis can be executed by two fundamentally distinct mechanisms. We will test this hypothesis by pursuing three specific aims: (i) defining the role of ACSL4 and related lipid metabolic enzymes in promoting ferroptosis in response to direct GPX4 inhibition, (ii) identifying cellular and molecular features that distinguish the two ferroptosis mechanisms in vitro and in vivo, and (iii) defining genes and processes that regulate ACSL4-independent ferroptosis in response to cystine deprivation. These studies will be carried out using cutting-edge chemical, genetic, functional genomic, lipidomic, and imaging tools and methods. This research will advance our fundamental understanding of ferroptosis, with the ultimate goal of improving human health.