title: E-Ras improves the efficiency of reprogramming by facilitating cell cycle progression through JNK-Sp1 pathway.
abstract: We have previously shown that pluripotent stem cells can be induced from adult somatic cells which were exposed to protein extracts isolated from mouse embryonic stem cells (mESC). Interestingly, generation of induced pluripotent stem (iPS) cells depended on the background of ES cell lines; possible by extracts from C57, but not from E14. Proteomic analysis of two different mES cell lines (C57 and E14) shows that embryonic Ras (E-Ras) is expressed differently in two mES cell lines; high level of E-Ras only in C57 mESC whose extracts allows iPS cells production from somatic cells. Here, we show that E-Ras augments the efficiency in reprogramming of fibroblast by promoting cell proliferation. We found that over-expression of E-Ras in fibroblast increased cell proliferation which was caused by specific up-regulation of cyclins D and E, not A or B, leading to the accelerated G1 to S phase transition. To figure out the common transcription factor of cyclins D and E, we used TRANSFAC database and selected SP1 as a candidate which was confirmed as enhancer of cyclins D and E by luciferase promoter assay using mutants. As downstream signaling pathways, E-Ras activated only c-Jun N-terminal kinases (JNK) but not ERK or p38. Inhibition of JNK prevented E-Ras-mediated induction of pSP1, cyclins D, E, and cell proliferation. Finally, E-Ras transduction to fibroblast enhanced the efficiency of iPS cell generation by 4 factors (Oct4/Klf4/Sox2/C-myc), which was prevented by JNK inhibitor. In conclusion, E-Ras stimulates JNK, enhances binding of Sp1 on the promoter of cyclins D and E, leading to cell proliferation. E-Ras/JNK axis is a critical mechanism to generate iPS cells by transduction of 4 factors or by treatment of mESC protein extracts.
authors.affiliation: National Research Laboratory for Stem Cell Niche, Seoul National University College of Medicine, Seoul, Republic of Korea; Innovative Research Institute for Cell Therapy, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Yoo-Wook
authors.initials: YW
authors.lastname: Kwon
authors.affiliation: National Research Laboratory for Stem Cell Niche, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Seulgi
authors.initials: S
authors.lastname: Jang
authors.affiliation: National Research Laboratory for Stem Cell Niche, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Jae-Seung
authors.initials: JS
authors.lastname: Paek
authors.affiliation: National Research Laboratory for Stem Cell Niche, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Jae-Woong
authors.initials: JW
authors.lastname: Lee
authors.affiliation: National Research Laboratory for Stem Cell Niche, Seoul National University College of Medicine, Seoul, Republic of Korea; Innovative Research Institute for Cell Therapy, Seoul National University Hospital, Seoul, Republic of Korea; Cardiovascular Center & Department of Internal Medicine, Seoul National University, Seoul, Republic of Korea.
authors.forename: Hyun-Jai
authors.initials: HJ
authors.lastname: Cho
authors.affiliation: National Research Laboratory for Stem Cell Niche, Seoul National University College of Medicine, Seoul, Republic of Korea; Innovative Research Institute for Cell Therapy, Seoul National University Hospital, Seoul, Republic of Korea; Cardiovascular Center & Department of Internal Medicine, Seoul National University, Seoul, Republic of Korea.
authors.forename: Han-Mo
authors.initials: HM
authors.lastname: Yang
authors.affiliation: National Research Laboratory for Stem Cell Niche, Seoul National University College of Medicine, Seoul, Republic of Korea; Innovative Research Institute for Cell Therapy, Seoul National University Hospital, Seoul, Republic of Korea; Cardiovascular Center & Department of Internal Medicine, Seoul National University, Seoul, Republic of Korea; Molecular Medicine & Biopharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea. Electronic address: hyosoo@snu.ac.kr.
authors.forename: Hyo-Soo
authors.initials: HS
authors.lastname: Kim
mesh_terms: D000818:Animals; D002453:Cell Cycle; D002454:Cell Differentiation; D006801:Humans; D000090062:Kruppel-Like Factor 4; D020935:MAP Kinase Signaling System / Q000235:genetics*; D051379:Mice; D015689:Oncogene Protein p21(ras) / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection
chemical_list: C474774:ERas protein, human; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D014157:Transcription Factors; D015689:Oncogene Protein p21(ras)
keywords: Cell cycle; Cell proliferation; E-Ras; ES cell; Reprogramming