title: P53 Regulates Rapid Apoptosis in Human Pluripotent Stem Cells.
abstract: Human pluripotent stem cells (hPSCs) are sensitive to DNA damage and undergo rapid apoptosis compared to their differentiated progeny cells. Here, we explore the underlying mechanisms for the increased apoptotic sensitivity of hPSCs that helps to determine pluripotent stem cell fate. Apoptosis was induced by exposure to actinomycin D, etoposide, or tunicamycin, with each agent triggering a distinct apoptotic pathway. We show that hPSCs are more sensitive to all three types of apoptosis induction than are lineage-non-specific, retinoic-acid-differentiated hPSCs. Also, Bax activation and pro-apoptotic mitochondrial intermembrane space protein release, which are required to initiate the mitochondria-mediated apoptosis pathway, are more rapid in hPSCs than in retinoic-acid-differentiated hPSCs. Surprisingly, Bak and not Bax is essential for actinomycin-D-induced apoptosis in human embryonic stem cells. Finally, P53 is degraded rapidly in an ubiquitin-proteasome-dependent pathway in hPSCs at steady state but quickly accumulates and induces apoptosis when Mdm2 function is impaired. Rapid degradation of P53 ensures the survival of healthy hPSCs but avails these cells for immediate apoptosis upon cellular damage by P53 stabilization. Altogether, we provide an underlying, interconnected molecular mechanism that primes hPSCs for quick clearance by apoptosis to eliminate hPSCs with unrepaired genome alterations and preserves organismal genomic integrity during the early critical stages of human embryonic development.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of California Los Angeles, 675 Charles Young Drive South, 4-762 MRL, Los Angeles, CA 90095, USA.
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Setoguchi
authors.affiliation: Molecular Biology Institute, University of California Los Angeles, 675 Charles Young Drive South, 4-762 MRL, Los Angeles, CA 90095, USA.
authors.forename: Tara
authors.initials: T
authors.lastname: TeSlaa
authors.affiliation: Molecular Biology Institute, University of California Los Angeles, 675 Charles Young Drive South, 4-762 MRL, Los Angeles, CA 90095, USA; Department of Chemistry and Biochemistry, University of California Los Angeles, 607 Charles Young Drive East, 4041A Young Hall, Los Angeles, CA 90095, USA; Jonsson Comprehensive Cancer Center, University of California Los Angeles, 675 Charles Young Drive South, 4-762 MRL, Los Angeles, CA 90095, USA.
authors.forename: Carla M
authors.initials: CM
authors.lastname: Koehler
authors.affiliation: Department of Pathology and Laboratory Medicine, University of California Los Angeles, 675 Charles Young Drive South, 4-762 MRL, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California Los Angeles, 675 Charles Young Drive South, 4-762 MRL, Los Angeles, CA 90095, USA; Jonsson Comprehensive Cancer Center, University of California Los Angeles, 675 Charles Young Drive South, 4-762 MRL, Los Angeles, CA 90095, USA; Department of Bioengineering, Department of Pediatrics, California NanoSystems Institute, and Broad Center for Regenerative Medicine and Stem Cell Research, University of California Los Angeles, 607 Charles Young Drive East, 4041A Young Hall, Los Angeles, CA 90095, USA. Electronic address: mteitell@mednet.ucla.edu.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Teitell
mesh_terms: D017209:Apoptosis; D015153:Blotting, Western; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D004249:DNA Damage / Q000235:genetics; D006801:Humans; D007124:Immunoenzyme Techniques; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology*; D039904:Pluripotent Stem Cells / Q000378:metabolism / Q000473:pathology*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2
keywords: Bak/Bax; cell fate; differentiation; mitochondria; pluripotency