title: Histone content increases in differentiating embryonic stem cells.
abstract: Mouse Embryonic Stem Cells (ESCs) are pluripotent mammalian cells derived from the Inner Cell Mass (ICM) of mouse blastocysts, which give rise to all three embryonic germ layers both in vivo and in vitro. Mouse ESCs have a distinct epigenetic landscape and a more decondensed chromatin compared to differentiated cells. Numerous studies have shown that distinct histone modifications in ESCs serve as hallmarks of pluripotency. However, so far it is still unknown whether the total histone content (as opposed to histone modifications) remains the same in cells of different developmental stage and differentiation capacity. In this work we show that total histone content differs between pluripotent and differentiated cells. In vitro spontaneous differentiation from ESCs to Embryoid Bodies (EBs) and directed differentiation toward neuronal and endodermal cells entails an increase in histone content. Primary MEFs also contain more histones than ESCs. We suggest that the difference in histone content is an additional hallmark of pluripotency, in addition to and besides histone modifications.
authors.affiliation: Chromatin Dynamics Unit, San Raffaele University and Research Institute Milan, Italy ; HMGBiotech Srl Milan, Italy.
authors.forename: Theodoros
authors.initials: T
authors.lastname: Karnavas
authors.affiliation: Core Facility for Conditional Mutagenesis, San Raffaele Research Institute Milan, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Pintonello
authors.affiliation: Chromatin Dynamics Unit, San Raffaele University and Research Institute Milan, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Agresti
authors.affiliation: Chromatin Dynamics Unit, San Raffaele University and Research Institute Milan, Italy ; Center for Translational Genomics, San Raffaele Research Institute Milan, Italy.
authors.forename: Marco E
authors.initials: ME
authors.lastname: Bianchi
keywords: Histones; development; differentiation; embryonic stem cells (ESCs); epigenetics