Kinome screen of ferroptosis reveals a novel role of ATM in regulating iron metabolism

Abstract

Ferroptosis is a specialized iron-dependent cell death that is associated with lethal lipid peroxidation. Modulation of ferroptosis may have therapeutic potential since it has been implicated in various human diseases as well as potential antitumor activities. However, much remains unknown about the underlying mechanisms and genetic determinants of ferroptosis. Given the critical role of kinases in most biological processes and the availability of various kinase inhibitors, we sought to systemically identify kinases essential for ferroptosis. We performed a forward genetic-based kinome screen against ferroptosis in MDA-MB-231 cells triggered by cystine deprivation. This screen identified 34 essential kinases involved in TNFα and NF-kB signaling. Unexpectedly, the DNA damage response serine/threonine kinase ATM (mutated in Ataxia-Telangiectasia) was found to be essential for ferroptosis. The pharmacological or genetic inhibition of ATM consistently rescued multiple cancer cells from ferroptosis triggered by cystine deprivation or erastin. Instead of the canonical DNA damage pathways, ATM inhibition rescued ferroptosis by increasing the expression of iron regulators involved in iron storage (ferritin heavy and light chain, FTH1 and FTL) and export (ferroportin, FPN1). The coordinated changes of these iron regulators during ATM inhibition resulted in a lowering of labile iron and prevented the irondependent ferroptosis. Furthermore, we found that ATM inhibition enhanced the nuclear translocation of metal-regulatory transcription factor 1 (MTF1), responsible for regulating expression of Ferritin/FPN1 and ferroptosis protection. Genetic depletion of MTF-1 abolished the regulation of iron-regulatory elements by ATM and resensitized the cells to ferroptosis. Together, we have identified an unexpected ATM-MTF1-Ferritin/FPN1 regulatory axis as novel determinants of ferroptosis through regulating labile iron levels.

Loss of ferritin in developing wing cells: Apoptosis and ferroptosis coincide

“…These results, along with the assumption that iron toxicity increases in ferritin H knockdown cells, suggest that ferritin H mutant cells die through the process of ferroptosis. Consistent with this idea, loss of ferritin is also required for erastin-induced ferroptosis in cancer cell lines [19].…”

MESH1 is a cytosolic NADPH phosphatase that regulates ferroptosis

“…Ferroptosis is a distinct form of iron-dependent cell death 5 that is triggered by oxidative stresses and characterized by the accumulation of lipid peroxidation products 14 . Even with the recent discovery of many genetic determinants [15][16][17][18]23,24 of ferroptosis by regulating lipid metabolism, iron availability, reactive oxygen species (ROS) and anti-oxidant capacity, much still remains unknown about the molecular mechanisms regulating ferroptosis. Our discovery of MESH1 as an NADPH phosphatase reveals an important role of the MESH1-mediated NADPH depletion and impairment of the glutathione regeneration in the execution of ferroptosis.…”

“…After establishing hMESH1 as a significant contributor to the cellular NADPH phosphatase activity and elucidating its molecular recognition of NADPH, we investigated whether the NADPH phosphatase activity of MESH1 plays a role in ferroptosis, a regulated form of cell death driven by the lethal accumulation of lipid hydroperoxides 14 . Various genetic determinants of ferroptosis have been identified [15][16][17][18] . Importantly, ferroptosis can be triggered by erastin, an inhibitor of the cystine importer xCT 5 , or by cystine deprivation, and is alleviated by high concentrations of NADPH 19 .…”

Inhibiting xCT/SLC7A11 induces ferroptosis of myofibroblastic hepatic stellate cells and protects against liver fibrosis

“…The aggregate data suggest that MF-HSCs may be more dependent on xCT to maintain levels of GSH that GPX4 requires to detoxify lipid peroxides than hepatocytes. It is interesting to note that Hippo transducers (YAP/TAZ) and ataxia telangiectasia mutated (ATM), factors previously shown to be critical for HSC transdifferentiation 36,37 , were also recently found to be critical for ferroptosis [38][39][40] , providing a potential mechanistic link between MF-HSC differentiation and ferroptosis vulnerability. Conversely, the relative resistance of hepatocytes to ferroptosis caused by xCT inhibition is supported by recent studies of hepatocyte toxicity caused by acetaminophen overdose, which revealed that hepatocytes predominately rely on the trans-sulfuration pathway to supply cystine to the redox system, and only induce xCT to import extracellular cystine when the trans-sulfuration pathway is impaired and unable to fulfill demands for GSH synthesis.…”