Jing Lu, Yi Li, Cristiana Mollinari, Enrico Garaci, Daniela Merlo and Gang Pei* Pages 934 - 949 ( 16 )
<P>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. </P><P> Objective: We aimed to study whether Aβ42O-induced mtDNA damage is involved in the regulation of stem cell differentiation. </P><P> 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. </P><P> 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 alteration. </P><P> 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 AD.</P>
Amyloid-β, mitochondria, DNA damage, DNA repair, human neural stem cell, differentiation.
State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, Department of Neuroscience, Istituto Superiore di Sanita, Rome, Telematic University San Raffaele, Via di Val Cannuta 247, 00166 Rome, Department of Neuroscience, Istituto Superiore di Sanita, Rome, State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031