title: Critical roles of Cyclin D1 in mouse embryonic fibroblast cell reprogramming.
abstract: Although pluripotent stem cells hold great promise in the fields of human disease modeling and regenerative medicine, the molecular basis of Oct-4, Sox2, Klf4, and c-Myc (OSKM)-induced cellular reprogramming remains unclear. To investigate the molecular mechanisms involved in cellular reprogramming, we studied the immediate effects of expression of the OSKM reprogramming factors on mouse embryonic fibroblasts (MEFs) in this study. Induction of the OSKM reprogramming factors significantly altered primary MEF growth properties. Although MEFs not expressing the reprogramming factors underwent replicative senescence within 9-12 days in culture, MEFs expressing the four reprogramming factors proliferated continuously throughout the duration of the experiment, suggesting that the expression of the OSKM reprogramming factors inhibits or delays replicative senescence. Cell cycle progression by the reprogramming factors was accompanied by the accumulation of Cyclin D1 through the early stages of reprogramming in MEFs, leading us to hypothesize that it might play a positive role in cellular reprogramming. Consistent with this hypothesis, forced Cyclin D1 expression enhanced reprogramming if administered concomitant with expression of the OSKM reprogramming factors. Most importantly, unlike wild-type MEFs expressing reprogramming factors, the number of emerging alkaline phosphatase-positive cyclin D1-null colonies was significantly reduced and cyclin D1-null MEFs were unable to initiate mesenchymal-to-epithelial transition. Our studies demonstrate that cyclin D1 is an essential gene in the reprogramming process and that activation of cyclin D1 by reprogramming factors is an important process for somatic cell reprogramming.
authors: Laboratory of Molecular and Cellular Biology, Department of Life Science, Sogang University, Seoul, Korea.
authors: Hye-Rim
authors: HR
authors: Oh
authors: Laboratory of Molecular and Cellular Biology, Department of Life Science, Sogang University, Seoul, Korea.
authors: Junghoon
authors: J
authors: Kim
authors: Laboratory of Molecular and Cellular Biology, Department of Life Science, Sogang University, Seoul, Korea.
authors: Jungho
authors: J
authors: Kim
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002453:Cell Cycle / Q000235:genetics; D049109:Cell Proliferation / Q000235:genetics; D002478:Cells, Cultured; D065150:Cellular Reprogramming / Q000235:genetics*; D016922:Cellular Senescence / Q000235:genetics; D019938:Cyclin D1 / Q000235:genetics* / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000235:genetics; D018345:Mice, Knockout; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D050814:Octamer Transcription Factor-3 / Q000235:genetics; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055748:SOXB1 Transcription Factors / Q000235:genetics; D013997:Time Factors
chemical_list: C530105:Ccnd1 protein, mouse; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; C489428:Myc protein, mouse; D050814:Octamer Transcription Factor-3; C494174:Pou5f1 protein, mouse; D016271:Proto-Oncogene Proteins c-myc; D055748:SOXB1 Transcription Factors; C527783:Sox2 protein, mouse; D019938:Cyclin D1
keywords: Cyclin D1; Epithelial-mesenchymal transition; cellular reprogramming; mouse embryonic fibroblasts; reprogramming factors; senescence