Dysregulated iron homeostasis Drives mitochondrial Injury and ferroptosis susceptibility in MELAS fibroblasts

Area of Science:

• Mitochondrial biology
• Cell death pathways
• Neurogenetics

Background:

• Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome, driven by mtDNA mutations, impairs mitochondrial function and increases oxidative stress.
• Ferroptosis, an iron-dependent cell death process, is implicated in MELAS pathology.

Purpose of the Study:

• To investigate the role of ferroptosis in MELAS patient-derived fibroblasts under mitochondrial stress.
• To explore the impact of iron dysregulation and potential therapeutic effects of iron chelation in MELAS.

Main Methods:

• Utilized MELAS patient-derived fibroblasts with varying heteroplasmy levels (MELAS^Low, MELAS^Hi) and normal human dermal fibroblasts (NHDF).
• Induced mitochondrial stress using rotenone (Complex I inhibitor).
• Assessed cell viability, reactive oxygen species (ROS), lipid peroxidation, iron levels, ferroptosis markers (GPX4, xCT, FSP1), iron homeostasis proteins (TFRC, DMT1), and mitochondrial morphology. Evaluated deferoxamine (DFO) treatment effects.

Main Results:

• Rotenone reduced cell viability and increased ROS and lipid peroxidation in MELAS fibroblasts.
• MELAS fibroblasts exhibited elevated Fe²⁺ accumulation, particularly MELAS^Hi cells.
• Ferroptosis was induced in rotenone-treated MELAS^Hi cells, with suppressed GPX4/xCT and downregulated FSP1.
• Iron homeostasis was dysregulated, evidenced by reduced TFRC and DMT1.
• Deferoxamine (DFO) treatment improved cell survival, attenuated mitochondrial fragmentation, and restored mitochondrial morphology.

Conclusions:

• Imbalances in Fe²⁺ and mitochondrial damage significantly amplify MELAS pathology.
• Iron chelation therapy represents a promising therapeutic strategy to reduce oxidative damage and preserve cellular viability in MELAS.