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Differentiation of Human Induced Pluripotent or Embryonic Stem Cells Decreases the DNA Damage Repair by Homologous Recombination.

ABSTRACT: The nitric oxide (NO)-cyclic GMP pathway contributes to human stem cell differentiation, but NO free radical production can also damage DNA, necessitating a robust DNA damage response (DDR) to ensure cell survival. How the DDR is affected by differentiation is unclear. Differentiation of stem cells, either inducible pluripotent or embryonic derived, increased residual DNA damage as determined by ?-H2AX and 53BP1 foci, with increased S-phase-specific chromosomal aberration after exposure to DNA-damaging agents, suggesting reduced homologous recombination (HR) repair as supported by the observation of decreased HR-related repair factor foci formation (RAD51 and BRCA1). Differentiated cells also had relatively increased fork stalling and R-loop formation after DNA replication stress. Treatment with NO donor (NOC-18), which causes stem cell differentiation has no effect on double-strand break (DSB) repair by non-homologous end-joining but reduced DSB repair by HR. Present studies suggest that DNA repair by HR is impaired in differentiated cells.

SUBMITTER: Mujoo K

PROVIDER: S-EPMC5831054 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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Differentiation of Human Induced Pluripotent or Embryonic Stem Cells Decreases the DNA Damage Repair by Homologous Recombination.

Mujoo Kalpana K Pandita Raj K RK Tiwari Anjana A Charaka Vijay V Chakraborty Sharmistha S Singh Dharmendra Kumar DK Hambarde Shashank S Hittelman Walter N WN Horikoshi Nobuo N Hunt Clayton R CR Khanna Kum Kum KK Kots Alexander Y AY Butler E Brian EB Murad Ferid F Pandita Tej K TK

Stem cell reports 20171102 5

The nitric oxide (NO)-cyclic GMP pathway contributes to human stem cell differentiation, but NO free radical production can also damage DNA, necessitating a robust DNA damage response (DDR) to ensure cell survival. How the DDR is affected by differentiation is unclear. Differentiation of stem cells, either inducible pluripotent or embryonic derived, increased residual DNA damage as determined by γ-H2AX and 53BP1 foci, with increased S-phase-specific chromosomal aberration after exposure to DNA-d ...[more]

PMID: 29103969

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Project description:BackgroundInduced pluripotent stem (iPS) cells have the capability to undergo self-renewal and differentiation into all somatic cell types. Since they can be produced through somatic cell reprogramming, which uses a defined set of transcription factors, iPS cells represent important sources of patient-specific cells for clinical applications. However, before these cells can be used in therapeutic designs, it is essential to understand their genetic stability.Methodology/principal findingsHere, we describe DNA damage responses in human iPS cells. We observe hypersensitivity to DNA damaging agents resulting in rapid induction of apoptosis after ?-irradiation. Expression of pluripotency factors does not appear to be diminished after irradiation in iPS cells. Following irradiation, iPS cells activate checkpoint signaling, evidenced by phosphorylation of ATM, NBS1, CHEK2, and TP53, localization of ATM to the double strand breaks (DSB), and localization of TP53 to the nucleus of NANOG-positive cells. We demonstrate that iPS cells temporary arrest cell cycle progression in the G(2) phase of the cell cycle, displaying a lack of the G(1)/S cell cycle arrest similar to human embryonic stem (ES) cells. Furthermore, both cell types remove DSB within six hours of ?-irradiation, form RAD51 foci and exhibit sister chromatid exchanges suggesting homologous recombination repair. Finally, we report elevated expression of genes involved in DNA damage signaling, checkpoint function, and repair of various types of DNA lesions in ES and iPS cells relative to their differentiated counterparts.Conclusions/significanceHigh degrees of similarity in DNA damage responses between ES and iPS cells were found. Even though reprogramming did not alter checkpoint signaling following DNA damage, dramatic changes in cell cycle structure, including a high percentage of cells in the S phase, increased radiosensitivity and loss of DNA damage-induced G(1)/S cell cycle arrest, were observed in stem cells generated by induced pluripotency.

Dataset Information

Differentiation of Human Induced Pluripotent or Embryonic Stem Cells Decreases the DNA Damage Repair by Homologous Recombination.

Publications

Differentiation of Human Induced Pluripotent or Embryonic Stem Cells Decreases the DNA Damage Repair by Homologous Recombination.

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