Hypoxia induces ferroptotic cell death mediated by activation of the inner mitochondrial membrane fission protein MTP18/Drp1 in invertebrates

Hypoxia and ischemia damage sensitive organelles such as mitochondria, and mitochondrial dysfunction contributes to metabolic disorders in crustaceans under hypoxia. The mechanisms associated with ferroptosis in hypoxic disorders have not been determined in crustaceans. In particular, the early molecular events of mitochondrial dynamics in crustaceans require clarification. In this study, two evolutionarily conserved mitochondrial fission proteins, Drp1 and MTP18, were identified in oriental river prawn (Macrobrachium nipponense). In vitro, ferroptosis-mediated impairment of mitochondrial membrane potential was induced by hypoxia in oriental river prawn hemocytes. In hypoxia-induced hemocytes, activation of Drp1 by increased phosphorylation at S616 was identified. Drp1 mitochondrial translocation also increased, and mitochondrial fusion-related protein expression decreased in vivo. Altered mitochondrial fission-fusion dynamics have been linked to mitochondrial dysfunction, inducing a classic ferroptosis mechanism. Marf overexpression or Drp1 knockdown protected against mitochondrial dysfunction and ferroptotic cell death in vitro. Furthermore, hypoxia-induced mitochondrial fission was verified to be driven by Drp1/MTP18 interaction. Under hypoxia, MTP18 transcription was increased by the binding of activated HIF-1α to hypoxia response elements in its promoter. Conjointly, MTP18 knockdown resulted in less apoptosis and decreased prawn mortality in gill tissue in vitro, suggesting that adaptation to hypoxia involves a vital function by MTP18. In conclusion, we uncovered a conserved role of mitochondrial fission in hypoxia-induced ferroptotic cell death. Therefore, we suggest that specific modulation of MTP18/DRP1-mediated mitochondrial dynamics might be a potential therapeutic strategy in hypoxic stress-induced tissue injury in invertebrates.