Nanog is dispensable for the generation of induced pluripotent stem cells.
Cellular reprogramming from somatic cells to induced pluripotent stem cells (iPSCs) can be achieved through forced expression of the transcription factors Oct4, Klf4, Sox2, and c-Myc (OKSM) [1-4]. These factors, in combination with environmental cues, induce a stable intrinsic pluripotency network that confers indefinite self-renewal capacity on iPSCs. In addition to Oct4 and Sox2, the homeodomain-containing transcription factor Nanog is an integral part of the pluripotency network [5-11]. Although Nanog expression is not required for the maintenance of pluripotent stem cells, it has been reported to be essential for the establishment of both embryonic stem cells (ESCs) from blastocysts and iPSCs from somatic cells [10, 12]. Here we revisit the role of Nanog in direct reprogramming. Surprisingly, we find that Nanog is dispensable for iPSC formation under optimized culture conditions. We further document that Nanog-deficient iPSCs are transcriptionally highly similar to wild-type iPSCs and support the generation of teratomas and chimeric mice. Lastly, we provide evidence that the presence of ascorbic acid in the culture media is critical for overcoming the previously observed reprogramming block of Nanog knockout cells.
Cancer Center, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA; Center for Regenerative Medicine, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA; Department of Pathology, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA; Harvard Stem Cell Institute, 1350 Massachusetts Avenue, Cambridge, MA 02138, USA.
Benjamin A
BA
Schwarz
Cancer Center, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA; Center for Regenerative Medicine, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA; Harvard Stem Cell Institute, 1350 Massachusetts Avenue, Cambridge, MA 02138, USA.
Ori
O
Bar-Nur
Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK; Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.
José C R
JC
Silva
Cancer Center, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA; Center for Regenerative Medicine, Massachusetts General Hospital, 185 Cambridge Street, Boston, MA 02114, USA; Harvard Stem Cell Institute, 1350 Massachusetts Avenue, Cambridge, MA 02138, USA; Howard Hughes Medical Institute and Department of Stem Cell and Regenerative Biology, 7 Divinity Avenue, Cambridge, MA 02138, USA. Electronic address: khochedlinger@helix.mgh.harvard.edu.
Konrad
K
Hochedlinger
D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D018929:Cell Culture Techniques / Q000379:methods*; D002478:Cells, Cultured; D065150:Cellular Reprogramming / Q000187:drug effects / Q000502:physiology*; D005347:Fibroblasts / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D018398:Homeodomain Proteins / Q000378:metabolism*; D057026:Induced Pluripotent Stem Cells / Q000378:metabolism*; D000090062:Kruppel-Like Factor 4; D051379:Mice; D018345:Mice, Knockout; D000071317:Nanog Homeobox Protein; D020411:Oligonucleotide Array Sequence Analysis
D018398:Homeodomain Proteins; C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D000071317:Nanog Homeobox Protein; C475540:Nanog protein, mouse; D001205:Ascorbic Acid