@article{MuenstThierWinnemoelleretal.2016,
  author    = {M{\"u}nst, Bernhard and Thier, Marc Christian and Winnem{\"o}ller, Dirk and Helfen, Martina and Thummer, Rajkumar P. and Edenhofer, Frank},
  title     = {Nanog induces suppression of senescence through downregulation of p27\(^{KIP1}\) expression},
  series = {Journal of Cell Science},
  volume    = {129},
  journal   = {Journal of Cell Science},
  number    = {5},
  doi       = {10.1242/jcs.167932},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-190761},
  pages     = {912-920},
  year      = {2016},
  abstract  = {A comprehensive analysis of the molecular network of cellular factors establishing and maintaining pluripotency as well as self renewal of pluripotent stem cells is key for further progress in understanding basic stem cell biology. Nanog is necessary for the natural induction of pluripotency in early mammalian development but dispensable for both its maintenance and its artificial induction. To gain further insight into the molecular activity of Nanog, we analyzed the outcomes of Nanog gain-of-function in various cell models employing a recently developed biologically active recombinant cell-permeant protein, Nanog-TAT. We found that Nanog enhances the proliferation of both NIH 3T3 and primary fibroblast cells. Nanog transduction into primary fibroblasts results in suppression of senescence-associated beta-galactosidase activity. Investigation of cell cycle factors revealed that transient activation of Nanog correlates with consistent downregulation of the cell cycle inhibitor p27\(^{KIP1}\) (also known as CDKN1B). By performing chromatin immunoprecipitation analysis, we confirmed bona fide Nanog-binding sites upstream of the p27\(^{KIP1}\) gene, establishing a direct link between physical occupancy and functional regulation. Our data demonstrates that Nanog enhances proliferation of fibroblasts through transcriptional regulation of cell cycle inhibitor p27 gene.},
  language  = {en}
}
@article{KadariLuLietal.2014,
  author    = {Kadari, Asifiqbal and Lu, Min and Li, Ming and Sekaran, Thileepan and Thummer, Rajkumar P. and Guyette, Naomi and Chu, Vi and Edenhofer, Frank},
  title     = {Excision of viral reprogramming cassettes by Cre protein transduction enables rapid, robust and efficient derivation of transgene-free human induced pluripotent stem cells},
  series = {Stem Cell Research \& Therapy},
  volume    = {5},
  journal   = {Stem Cell Research \& Therapy},
  number    = {2},
  issn      = {1757-6512},
  doi       = {10.1186/scrt435},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-120578},
  pages     = {47},
  year      = {2014},
  abstract  = {Integrating viruses represent robust tools for cellular reprogramming; however, the presence of viral transgenes in induced pluripotent stem cells (iPSCs) is deleterious because it holds the risk of insertional mutagenesis leading to malignant transformation. Here, we combine the robustness of lentiviral reprogramming with the efficacy of Cre recombinase protein transduction to derive iPSCs devoid of transgenes. By genome-wide analysis and targeted differentiation towards the cardiomyocyte lineage, we show that transgene-free iPSCs are superior to iPSCs before Cre transduction. Our study provides a simple, rapid and robust protocol for the generation of clinical-grade iPSCs suitable for disease modeling, tissue engineering and cell replacement therapies.},
  language  = {en}
}
@article{PeitzMuenstThummeretal.2014,
  author    = {Peitz, Michael and M{\"u}nst, Bernhard and Thummer, Rajkumar P. and Helfen, Martina and Edenhofer, Frank},
  title     = {Cell-permeant recombinant Nanog protein promotes pluripotency by inhibiting endodermal specification},
  series = {Stem Cell Research},
  volume    = {12},
  journal   = {Stem Cell Research},
  number    = {3},
  issn      = {1876-7753},
  doi       = {10.1016/j.scr.2014.02.006},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-119740},
  pages     = {680-689},
  year      = {2014},
  abstract  = {A comprehensive understanding of the functional network of transcription factors establishing and maintaining pluripotency is key for the development of biomedical applications of stem cells. Nanog plays an important role in early development and is essential to induce natural pluripotency in embryonic stem cells (ESCs). Inducible gain-of-function systems allowing a precise control over time and dosage of Nanog activity would be highly desirable to study its vital role in the establishment and maintenance of pluripotency at molecular level. Here we engineered a recombinant cell permeable version of Nanog by fusing it with the cell penetrating peptide TAT. Nanog-TAT can be readily expressed in and purified from E. coli and binds to a consensus Nanog DNA sequence. At cellular level it enhances proliferation and self-renewal of ESCs in the absence of leukemia inhibitory factor (LIF). Nanog-TAT together with LIF acts synergistically as judged by enhanced clonogenicity and activation of an Oct4-promoter-driven GFP reporter gene. Furthermore Nanog-TAT, in the absence of LIF, promotes pluripotency by inhibiting endodermal specification in a Stat3-independent manner. Our results demonstrate that Nanog protein transduction is an attractive tool allowing control over dose and time of addition to the cells for studying the molecular control of pluripotency without genetic manipulation.},
  language  = {en}
}