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Generation of Human Neurons and Oligodendrocytes from Pluripotent Stem Cells for Modeling Neuron-Oligodendrocyte Interactions
Published on: November 9, 2020
Amyloid-β Oligomers-induced Mitochondrial DNA Repair Impairment Contributes to Altered Human Neural Stem Cell
Jing Lu1, Yi Li1,2, Cristiana Mollinari3,4
1State 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, China.
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 alteration.
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.
Insights
Amyloid-β42 oligomers damage mitochondrial DNA in neural stem cells, impairing repair and altering differentiation. Stimulating DNA repair counteracts this neurotoxicity, offering a potential Alzheimer's treatment target.
Area of Science:
- Neuroscience
- Stem Cell Biology
- Mitochondrial Biology
Background:
- Amyloid-β42 oligomers (Aβ42O) are key neurotoxins in Alzheimer's disease (AD).
- Aβ42O induce mitochondrial oxidative stress, DNA damage, and affect stem cell properties.
- The role of Aβ42O-induced mitochondrial DNA (mtDNA) damage in stem cell differentiation is unclear.
Purpose of the Study:
- To investigate if Aβ42O-induced mtDNA damage regulates neural stem cell (NSC) differentiation.
- To explore the mechanisms of mtDNA damage and repair in response to Aβ42O.
- To assess the therapeutic potential of modulating mtDNA repair pathways.
Main Methods:
- Used human induced pluripotent stem cell (iPSC)-derived neural stem cells (NSCs).
- Assessed reactive oxygen species (ROS) and mtDNA damage via mitoSOX and PCR assays.
- Measured mtDNA repair (non-homologous end joining - NHEJ) activity, protein expression, and NSC differentiation markers (Tuj-1, GFAP).
Main Results:
- Aβ42O treatment increased ROS and mtDNA damage in NSCs, impairing NHEJ activity.
- NHEJ components (Ku70/80, DNA-PKcs, XRCC4) localize to mitochondria; XRCC4 silencing worsened mtDNA damage.
- Phytic Acid (IP6) pre-treatment inhibited Aβ42O-induced mtDNA damage and altered neuronal differentiation.
Conclusions:
- Aβ42O-induced mtDNA repair impairment shifts human NSC differentiation towards astrocytes.
- Stimulating mtDNA repair pathways counteracts Aβ42O neurotoxicity.
- mtDNA repair pathways represent a potential therapeutic target for AD and other neurodegenerative diseases.
