title: High basal γH2AX levels sustain self-renewal of mouse embryonic and induced pluripotent stem cells.
abstract: Phosphorylation of histone H2AX (γH2AX) is known to be the earliest indicator of DNA double-strand breaks. Recently, it has been shown that mouse embryonic stem cells (mESCs) have very high basal levels of γH2AX, even when they have not been exposed to genotoxic agents. As the specialized role of high basal γH2AX levels in pluripotent stem cells is still debated, we investigated whether H2AX phosphorylation is important in maintaining self-renewal of these cells. Here, we report that not only mESCs but also mouse-induced pluripotent stem cells (miPSCs), have high basal levels of γH2AX. We show that basal γH2AX levels decrease upon ESC and iPSC differentiation and increase when the cells are treated with self-renewal-enhancing small molecules. We observe that self-renewal activity is highly compromised in H2AX-/- cells and that it can be restored in these cells through reconstitution with a wild-type, but not a phospho-mutated, H2AX construct. Taken together, our findings suggest a novel function of H2AX that expands the knowledge of this histone variant beyond its role in DNA damage and into a new specialized biological function in mouse pluripotent stem cells.
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Turin, Italy. valentina.turinetto@unito.it
authors.forename: Valentina
authors.initials: V
authors.lastname: Turinetto
authors.forename: Luca
authors.initials: L
authors.lastname: Orlando
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Sanchez-Ripoll
authors.forename: Benjamin
authors.initials: B
authors.lastname: Kumpfmueller
authors.forename: Michael P
authors.initials: MP
authors.lastname: Storm
authors.forename: Paola
authors.initials: P
authors.lastname: Porcedda
authors.forename: Valentina
authors.initials: V
authors.lastname: Minieri
authors.forename: Silvia
authors.initials: S
authors.lastname: Saviozzi
authors.forename: Lisa
authors.initials: L
authors.lastname: Accomasso
authors.forename: Elisa
authors.initials: E
authors.lastname: Cibrario Rocchietti
authors.forename: Kim
authors.initials: K
authors.lastname: Moorwood
authors.forename: Paola
authors.initials: P
authors.lastname: Circosta
authors.forename: Alessandro
authors.initials: A
authors.lastname: Cignetti
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Welham
authors.forename: Claudia
authors.initials: C
authors.lastname: Giachino
mesh_terms: D000818:Animals; D004249:DNA Damage / Q000235:genetics; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism*; D005434:Flow Cytometry; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D057026:Induced Pluripotent Stem Cells / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D018613:Microscopy, Confocal; D010766:Phosphorylation
chemical_list: D006657:Histones; C475961:gamma-H2AX protein, mouse