Dysregulation of mitochondrial dynamics in cortical neurons derived from familial Alzheimer’s disease hiPSCs

Mitochondrial dynamics are essential in Alzheimer’s disease (AD). We differentiated hiPSCs from familial AD patients with PSEN1 variants (p.T119I, p.A246E, p.M146L) and controls into cortical i3-neurons using doxycycline-inducible NGN2, validated by pan-neuronal (TUJ1, MAP2, NeuN) and cortical (TBR1, CTIP2) markers. RT-qPCR of mitochondrial dynamics genes showed high baseline variability among controls. Nonetheless, fAD neurons showed convergent OPA1 downregulation alongside line-specific changes in DLP1, FIS1, and PINK1. Protein levels showed consistently reduced OPA1, whereas DLP1 increased in p.T119I and p.M146L, demonstrating a transcriptional-translational dissociation. Flow cytometry (TMRE and CellROX) confirmed consistent mitochondrial function in controls. Conversely, fAD neurons showed mutation-dependent functional divergence: p.T119I displayed marked mitochondrial membrane potential (ΔΨ_m) depolarization, whereas p.A246E and p.M146L exhibited elevated baseline ROS and decreased ΔΨ_m. Paraquat exposure (50 µM) revealed blunted mitochondrial adaptability and impaired redox response in mutants. Our findings demonstrate a transcriptional-translational dissociation in fusion/fission regulation, indicating that distinct PSEN1 variants affecting different domains generate divergent mitochondrial phenotypes and impairment in i3-neurons.