title: The histone chaperone CAF-1 safeguards somatic cell identity.
abstract: Cellular differentiation involves profound remodelling of chromatic landscapes, yet the mechanisms by which somatic cell identity is subsequently maintained remain incompletely understood. To further elucidate regulatory pathways that safeguard the somatic state, we performed two comprehensive RNA interference (RNAi) screens targeting chromatin factors during transcription-factor-mediated reprogramming of mouse fibroblasts to induced pluripotent stem cells (iPS cells). Subunits of the chromatin assembly factor-1 (CAF-1) complex, including Chaf1a and Chaf1b, emerged as the most prominent hits from both screens, followed by modulators of lysine sumoylation and heterochromatin maintenance. Optimal modulation of both CAF-1 and transcription factor levels increased reprogramming efficiency by several orders of magnitude and facilitated iPS cell formation in as little as 4 days. Mechanistically, CAF-1 suppression led to a more accessible chromatin structure at enhancer elements early during reprogramming. These changes were accompanied by a decrease in somatic heterochromatin domains, increased binding of Sox2 to pluripotency-specific targets and activation of associated genes. Notably, suppression of CAF-1 also enhanced the direct conversion of B cells into macrophages and fibroblasts into neurons. Together, our findings reveal the histone chaperone CAF-1 to be a novel regulator of somatic cell identity during transcription-factor-induced cell-fate transitions and provide a potential strategy to modulate cellular plasticity in a regenerative setting.
authors.affiliation: Department of Molecular Biology, Cancer Center and Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.|Department of Stem Cell and Regenerative Biology and Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA.|Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA.
authors.forename: Sihem
authors.initials: S
authors.lastname: Cheloufi
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), A-1030 Vienna, Austria.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Elling
authors.affiliation: Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), A-1030 Vienna, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Hopfgartner
authors.affiliation: Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts 02115, USA.|Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: Youngsook L
authors.initials: YL
authors.lastname: Jung
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.|Division of Newborn Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: Jernej
authors.initials: J
authors.lastname: Murn
authors.affiliation: California Institute of Technology, Division of Biology and Biological Engineering, Pasadena, California 91125, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Ninova
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), A-1030 Vienna, Austria.
authors.forename: Maria
authors.initials: M
authors.lastname: Hubmann
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.|Division of Newborn Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: Aimee I
authors.initials: AI
authors.lastname: Badeaux
authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine, Department of Pathology and Department of Bioengineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Cheen
authors.initials: C
authors.lastname: Euong Ang
authors.affiliation: Department of Stem Cell and Regenerative Biology and Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA.|Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts 02142, USA.
authors.forename: Danielle
authors.initials: D
authors.lastname: Tenen
authors.affiliation: Department of Molecular Biology, Cancer Center and Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.|Department of Stem Cell and Regenerative Biology and Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA.|Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Wesche
authors.affiliation: Department of Molecular Biology, Cancer Center and Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.|Department of Stem Cell and Regenerative Biology and Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA.|Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA.
authors.forename: Nadezhda
authors.initials: N
authors.lastname: Abazova
authors.affiliation: Department of Molecular Biology, Cancer Center and Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.|Department of Stem Cell and Regenerative Biology and Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA.|Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA.
authors.forename: Max
authors.initials: M
authors.lastname: Hogue
authors.affiliation: Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA.
authors.forename: Nilgun
authors.initials: N
authors.lastname: Tasdemir
authors.affiliation: Department of Molecular Biology, Cancer Center and Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.|Department of Stem Cell and Regenerative Biology and Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA.|Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Brumbaugh
authors.affiliation: Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), A-1030 Vienna, Austria.
authors.forename: Philipp
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authors.lastname: Rathert
authors.affiliation: Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), A-1030 Vienna, Austria.
authors.forename: Julian
authors.initials: J
authors.lastname: Jude
authors.affiliation: Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts 02115, USA.|Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: Francesco
authors.initials: F
authors.lastname: Ferrari
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.|Division of Newborn Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: Andres
authors.initials: A
authors.lastname: Blanco
authors.affiliation: Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), A-1030 Vienna, Austria.
authors.forename: Michaela
authors.initials: M
authors.lastname: Fellner
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), A-1030 Vienna, Austria.
authors.forename: Daniel
authors.initials: D
authors.lastname: Wenzel
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), A-1030 Vienna, Austria.
authors.forename: Marietta
authors.initials: M
authors.lastname: Zinner
authors.affiliation: The Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, New York 10016, USA.
authors.forename: Simon E
authors.initials: SE
authors.lastname: Vidal
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), A-1030 Vienna, Austria.
authors.forename: Oliver
authors.initials: O
authors.lastname: Bell
authors.affiliation: The Helen L. and Martin S. Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, New York 10016, USA.
authors.forename: Matthias
authors.initials: M
authors.lastname: Stadtfeld
authors.affiliation: Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA.|Center for Personal Dynamic Regulomes and Program in Epithelial Biology, Stanford University School of Medicine, Stanford, California 94305, USA.
authors.forename: Howard Y
authors.initials: HY
authors.lastname: Chang
authors.affiliation: Centre de Recherche, Institut Curie, 75248 Paris, France.
authors.forename: Genevieve
authors.initials: G
authors.lastname: Almouzni
authors.affiliation: Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA.|Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA.
authors.forename: Scott W
authors.initials: SW
authors.lastname: Lowe
authors.affiliation: Department of Stem Cell and Regenerative Biology and Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA.|Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts 02142, USA.
authors.forename: John
authors.initials: J
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authors.affiliation: Institute for Stem Cell Biology and Regenerative Medicine, Department of Pathology and Department of Bioengineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Marius
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authors.lastname: Wernig
authors.affiliation: California Institute of Technology, Division of Biology and Biological Engineering, Pasadena, California 91125, USA.
authors.forename: Alexei
authors.initials: A
authors.lastname: Aravin
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.|Division of Newborn Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Department of Biomedical Informatics, Harvard Medical School, Boston, Massachusetts 02115, USA.|Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Park
authors.affiliation: Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), A-1030 Vienna, Austria.
authors.forename: Josef M
authors.initials: JM
authors.lastname: Penninger
authors.affiliation: Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), A-1030 Vienna, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Zuber
authors.affiliation: Department of Molecular Biology, Cancer Center and Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.|Department of Stem Cell and Regenerative Biology and Harvard Stem Cell Institute, Cambridge, Massachusetts 02138, USA.|Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA.
authors.forename: Konrad
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authors.lastname: Hochedlinger
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D065150:Cellular Reprogramming / Q000235:genetics*; D002843:Chromatin / Q000378:metabolism; D056504:Chromatin Assembly Factor-1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics; D006570:Heterochromatin / Q000378:metabolism; D051379:Mice; D009707:Nucleosomes / Q000378:metabolism; D034622:RNA Interference; D014161:Transduction, Genetic
chemical_list: D002843:Chromatin; D056504:Chromatin Assembly Factor-1; D006570:Heterochromatin; D009707:Nucleosomes