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Iron‐induced NCOA4 condensation regulates ferritin fate and iron homeostasis
Author(s) -
Kuno Sota,
Fujita Hiroaki,
Tanaka Yuki,
Ogra Yasumitsu,
Iwai Kazuhiro
Publication year - 2022
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.15252/embr.202154278
Subject(s) - conceptualization , library science , fujita scale , political science , chemistry , computer science , artificial intelligence , meteorology , physics
Iron is not only essential but also a toxic trace element. Under iron repletion, ferritin maintains cellular iron homeostasis by storing iron to avoid iron toxicity. Under iron depletion, the ferritin‐specific autophagy adaptor NCOA4 delivers ferritin to lysosomes via macroautophagy to enable cells to use stored iron. Here, we show that NCOA4 also plays crucial roles in the regulation of ferritin fate under iron repletion. NCOA4 forms insoluble condensates via multivalent interactions generated by the binding of iron to its intrinsically disordered region. This sequesters NCOA4 away from ferritin and allows ferritin accumulation in the early phase of iron repletion. Under prolonged iron repletion, NCOA4 condensates can deliver ferritin to lysosomes via a TAX1BP1‐dependent non‐canonical autophagy pathway, thereby preventing relative iron deficiency due to excessive iron storage and reduced iron uptake. Together, these observations suggest that the NCOA4‐ferritin axis modulates intracellular iron homeostasis in accordance with cellular iron availability.