title: Lineage conversion induced by pluripotency factors involves transient passage through an iPSC stage.
abstract: Brief expression of pluripotency-associated factors such as Oct4, Klf4, Sox2 and c-Myc (OKSM), in combination with differentiation-inducing signals, has been reported to trigger transdifferentiation of fibroblasts into other cell types. Here we show that OKSM expression in mouse fibroblasts gives rise to both induced pluripotent stem cells (iPSCs) and induced neural stem cells (iNSCs) under conditions previously shown to induce only iNSCs. Fibroblast-derived iNSC colonies silenced retroviral transgenes and reactivated silenced X chromosomes, both hallmarks of pluripotent stem cells. Moreover, lineage tracing with an Oct4-CreER labeling system demonstrated that virtually all iNSC colonies originated from cells transiently expressing Oct4, whereas ablation of Oct4(+) cells prevented iNSC formation. Lastly, an alternative transdifferentiation cocktail that lacks Oct4 and was reportedly unable to support induced pluripotency yielded iPSCs and iNSCs carrying the Oct4-CreER-derived lineage label. Together, these data suggest that iNSC generation from fibroblasts using OKSM and other pluripotency-related reprogramming factors requires passage through a transient iPSC state.
authors.affiliation: 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.
authors.forename: Ori
authors.initials: O
authors.lastname: Bar-Nur
authors.affiliation: 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.
authors.forename: Cassandra
authors.initials: C
authors.lastname: Verheul
authors.affiliation: 1] Center for Regenerative Medicine (CReM), Boston University School of Medicine, Boston, Massachusetts, USA. [2] Boston Medical Center, Boston, Massachusetts, USA.
authors.forename: Andreia G
authors.initials: AG
authors.lastname: Sommer
authors.affiliation: 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Brumbaugh
authors.affiliation: 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Schwarz
authors.affiliation: 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.
authors.forename: Inna
authors.initials: I
authors.lastname: Lipchina
authors.affiliation: 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Huebner
authors.affiliation: 1] Center for Regenerative Medicine (CReM), Boston University School of Medicine, Boston, Massachusetts, USA. [2] Boston Medical Center, Boston, Massachusetts, USA.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Mostoslavsky
authors.affiliation: 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA.
authors.forename: Konrad
authors.initials: K
authors.lastname: Hochedlinger
mesh_terms: D000818:Animals; D054338:Cell Transdifferentiation / Q000502:physiology*; D002478:Cells, Cultured; D005260:Female; D005347:Fibroblasts / Q000502:physiology; D020868:Gene Silencing; D057026:Induced Pluripotent Stem Cells / Q000502:physiology*; D000090062:Kruppel-Like Factor 4; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D014157:Transcription Factors / Q000378:metabolism*; D019076:Transgenes
chemical_list: C000715468:Klf4 protein, mouse; D000090062:Kruppel-Like Factor 4; D014157:Transcription Factors