Background: Amyloid-β42 oligomers (Aβ42O), the proximate effectors of neurotoxicity observed
in Alzheimer’s disease (AD), can induce mitochondrial oxidative stress and impair mitochondrial
function besides causing mitochondrial DNA (mtDNA) damage. Aβ42O also regulate the proliferative
and differentiative properties of stem cells.
Objective: We aimed to study whether Aβ42O-induced mtDNA damage is involved in the regulation of
stem cell differentiation.
Method: Human iPSCs-derived neural stem cell (NSC) was applied to investigate the effect of Aβ42O on
reactive oxygen species (ROS) production and DNA damage using mitoSOX staining and long-range
PCR lesion assay, respectively. mtDNA repair activity was measured by non-homologous end joining
(NHEJ) in vitro assay using mitochondria isolates and the expression and localization of NHEJ components
were determined by Western blot and immunofluorescence assay. The expressions of Tuj-1 and
GFAP, detected by immunofluorescence and qPCR, respectively, were examined as an index of neurons
and astrocytes production.
Results: We show that in NSC Aβ42O treatment induces ROS production and mtDNA damage and impairs
DNA end joining activity. NHEJ components, such as Ku70/80, DNA-PKcs, and XRCC4, are localized
in mitochondria and silencing of XRCC4 significantly exacerbates the effect of Aβ42O on
mtDNA integrity. On the contrary, pre-treatment with Phytic Acid (IP6), which specifically stimulates
DNA-PK-dependent end-joining, inhibits Aβ42O-induced mtDNA damage and neuronal differentiation
Conclusion: Aβ42O-induced mtDNA repair impairment may change cell fate thus shifting human NSC
differentiation toward an astrocytic lineage. Repair stimulation counteracts Aβ42O neurotoxicity, suggesting
mtDNA repair pathway as a potential target for the treatment of neurodegenerative disorders like