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

Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome, caused by mtDNA mutations, disrupts mitochondrial function and triggers oxidative stress. This study explores ferroptosis playing a key role in cell death in MELAS patient-derived fibroblasts harboring low (MELASLow) or high (MELASHi) heteroplasmy levels, subjected to rotenone-induced mitochondrial stress (a Complex I inhibitor). Rotenone crucially curtailed cell viability in MELAS fibroblasts relative to normal human dermal fibroblasts (NHDF), alongside elevated cellular/mitochondrial reactive oxygen species (ROS), lipid peroxidation, stable SOD1, and mildly diminished SOD2 in MELASHi cells. Rotenone induced selective Fe2+ accumulation in MELASLow cells, while MELASHi showed exacerbated Fe2+ elevation both at baseline and rotenone-treated conditions. Ferroptosis susceptibility was evident in rotenone-treated MELASHi via suppressed glutathione peroxidase 4 (GPX4) and cystine/glutamate antiporter (xCT); ferroptosis suppressor FSP1 was downregulated across MELAS subtypes versus NHDF. Iron homeostasis was dysregulated, with compensatory transferrin receptor (TFRC) and divalent metal transporter 1 (DMT1) reductions in MELAS cells. Non-toxic deferoxamine (DFO; 1-100 μM) pretreatment reversed cell survival, attenuated mitochondrial fragmentation, and restored elongated morphology in the stressed MELAS fibroblasts. These data establish the imbalance of Fe2+ and mitochondrial damages are central amplifier of MELAS pathology, positioning iron chelation as a viable therapeutic to mitigate oxidative harm and safeguard cellular viability.