title: Zscan4 promotes genomic stability during reprogramming and dramatically improves the quality of iPS cells as demonstrated by tetraploid complementation.
abstract: Induced pluripotent stem (iPS) cells generated using Yamanaka factors have great potential for use in autologous cell therapy. However, genomic abnormalities exist in human iPS cells, and most mouse iPS cells are not fully pluripotent, as evaluated by the tetraploid complementation assay (TCA); this is most likely associated with the DNA damage response (DDR) occurred in early reprogramming induced by Yamanaka factors. In contrast, nuclear transfer can faithfully reprogram somatic cells into embryonic stem (ES) cells that satisfy the TCA. We thus hypothesized that factors involved in oocyte-induced reprogramming may stabilize the somatic genome during reprogramming, and improve the quality of the resultant iPS cells. To test this hypothesis, we screened for factors that could decrease DDR signals during iPS cell induction. We determined that Zscan4, in combination with the Yamanaka factors, not only remarkably reduced the DDR but also markedly promoted the efficiency of iPS cell generation. The inclusion of Zscan4 stabilized the genomic DNA, resulting in p53 downregulation. Furthermore, Zscan4 also enhanced telomere lengthening as early as 3 days post-infection through a telomere recombination-based mechanism. As a result, iPS cells generated with addition of Zscan4 exhibited longer telomeres than classical iPS cells. Strikingly, more than 50% of iPS cell lines (11/19) produced via this "Zscan4 protocol" gave rise to live-borne all-iPS cell mice as determined by TCA, compared to 1/12 for lines produced using the classical Yamanaka factors. Our findings provide the first demonstration that maintaining genomic stability during reprogramming promotes the generation of high quality iPS cells.
authors.affiliation: Group of Epigenetic Reprogramming, State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Jiang
authors.forename: Wenjian
authors.initials: W
authors.lastname: Lv
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Ye
authors.forename: Lingbo
authors.initials: L
authors.lastname: Wang
authors.forename: Man
authors.initials: M
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Yang
authors.forename: Maja
authors.initials: M
authors.lastname: Okuka
authors.forename: Chikai
authors.initials: C
authors.lastname: Zhou
authors.forename: Xuan
authors.initials: X
authors.lastname: Zhang
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
authors.forename: Jinsong
authors.initials: J
authors.lastname: Li
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D065150:Cellular Reprogramming; D004260:DNA Repair; D042822:Genomic Instability; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology*; D051379:Mice; D016615:Telomere / Q000378:metabolism; D013724:Teratoma / Q000473:pathology; D057891:Tetraploidy; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; C581714:Zscan4f protein, mouse