title: Nanog overcomes reprogramming barriers and induces pluripotency in minimal conditions.
abstract: Induced pluripotency requires the expression of defined factors and culture conditions that support the self-renewal of embryonic stem (ES) cells. Small molecule inhibition of MAP kinase (MEK) and glycogen synthase kinase 3 (GSK3) with LIF (2i/LIF) provides an optimal culture environment for mouse ES cells and promotes transition to naive pluripotency in partially reprogrammed (pre-iPS) cells. Here we show that 2i/LIF treatment in clonal lines of pre-iPS cells results in the activation of endogenous Nanog and rapid downregulation of retroviral Oct4 expression. Nanog enables somatic cell reprogramming in serum-free medium supplemented with LIF, a culture condition which does not support induced pluripotency or the self-renewal of ES cells, and is sufficient to reprogram epiblast-derived stem cells to naive pluripotency in serum-free medium alone. Nanog also enhances reprogramming in cooperation with kinase inhibition or 5-aza-cytidine, a small molecule inhibitor of DNA methylation. These results highlight the capacity of Nanog to overcome multiple barriers to reprogramming and reveal a synergy between Nanog and chemical inhibitors that promote reprogramming. We conclude that Nanog induces pluripotency in minimal conditions. This provides a strategy for imposing naive pluripotency in mammalian cells independently of species-specific culture requirements.
authors.affiliation: Wellcome Trust Centre for Stem Cell Research and Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.
authors.forename: Thorold W
authors.initials: TW
authors.lastname: Theunissen
authors.forename: Anouk L
authors.initials: AL
authors.lastname: van Oosten
authors.forename: Gonçalo
authors.initials: G
authors.lastname: Castelo-Branco
authors.forename: John
authors.initials: J
authors.lastname: Hall
authors.forename: Austin
authors.initials: A
authors.lastname: Smith
authors.forename: José C R
authors.initials: JC
authors.lastname: Silva
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D019175:DNA Methylation; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D000071317:Nanog Homeobox Protein; D039904:Pluripotent Stem Cells / Q000166:cytology* / Q000378:metabolism*
chemical_list: D018398:Homeodomain Proteins; D000071317:Nanog Homeobox Protein; C475540:Nanog protein, mouse