Abstract
Pluripotent human embryonic stem (hES) cells require mechanisms to maintain genomic integrity in response to DNA damage that could compromise competency for lineage-commitment, development, and tissue-renewal. The mechanisms that protect the genome in rapidly proliferating hES cells are minimally understood. Human ES cells have an abbreviated cell cycle with a very brief G1 period suggesting that mechanisms mediating responsiveness to DNA damage may deviate from those in somatic cells. Here, we investigated how hES cells react to DNA damage induced by ionizing radiation (IR) and whether genomic insult evokes DNA repair pathways and/or cell death. We find that hES cells respond to DNA damage by rapidly inducing Caspase-3 and -8, phospho-H2AX foci, phosphorylation of p53 on Ser15 and p21 mRNA levels, as well as concomitant cell cycle arrest in G2 based on Ki67 staining and FACS analysis. Unlike normal somatic cells, hES cells and cancer cells robustly express the anti-apoptotic protein Survivin, consistent with the immortal growth phenotype. SiRNA depletion of Survivin diminishes hES survival post-irradiation. Thus, our findings provide insight into pathways and processes that are activated in human embryonic stem cells upon DNA insult to support development and tissue regeneration.
Publication types
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Comparative Study
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Research Support, N.I.H., Extramural
MeSH terms
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Ataxia Telangiectasia Mutated Proteins
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Caspase 3 / metabolism
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Caspase 8 / metabolism
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Cell Cycle / radiation effects
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Cell Cycle Proteins / metabolism
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Cell Line
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Cell Line, Tumor
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Cell Proliferation / radiation effects*
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Cell Survival
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Cyclin-Dependent Kinase Inhibitor p21 / metabolism
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DNA Damage*
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DNA-Binding Proteins / metabolism
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Embryonic Stem Cells / metabolism
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Embryonic Stem Cells / radiation effects*
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Histones / metabolism
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Humans
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Inhibitor of Apoptosis Proteins
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Microtubule-Associated Proteins / genetics
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Microtubule-Associated Proteins / metabolism
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Phosphorylation
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Protein Serine-Threonine Kinases / metabolism
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RNA Interference
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Signal Transduction / radiation effects*
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Survivin
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Transfection
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Tumor Suppressor Protein p53 / metabolism
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Tumor Suppressor Proteins / metabolism
Substances
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BIRC5 protein, human
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CDKN1A protein, human
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Cell Cycle Proteins
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Cyclin-Dependent Kinase Inhibitor p21
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DNA-Binding Proteins
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H2AX protein, human
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Histones
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Inhibitor of Apoptosis Proteins
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Microtubule-Associated Proteins
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Survivin
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TP53 protein, human
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Tumor Suppressor Protein p53
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Tumor Suppressor Proteins
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ATM protein, human
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Ataxia Telangiectasia Mutated Proteins
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Protein Serine-Threonine Kinases
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CASP3 protein, human
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CASP8 protein, human
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Caspase 3
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Caspase 8