title: Gcm/Glide-dependent conversion into glia depends on neural stem cell age, but not on division, triggering a chromatin signature that is conserved in vertebrate glia.
abstract: Neurons and glia differentiate from multipotent precursors called neural stem cells (NSCs), upon the activation of specific transcription factors. In vitro, it has been shown that NSCs display very plastic features; however, one of the major challenges is to understand the bases of lineage restriction and NSC plasticity in vivo, at the cellular level. We show here that overexpression of the Gcm transcription factor, which controls the glial versus neuronal fate choice, fully and efficiently converts Drosophila NSCs towards the glial fate via an intermediate state. Gcm acts in a dose-dependent and autonomous manner by concomitantly repressing the endogenous program and inducing the glial program in the NSC. Most NSCs divide several times to build the embryonic nervous system and eventually enter quiescence: strikingly, the gliogenic potential of Gcm decreases with time and quiescent NSCs are resistant to fate conversion. Together with the fact that Gcm is able to convert mutant NSCs that cannot divide, this indicates that plasticity depends on temporal cues rather than on the mitotic potential. Finally, NSC plasticity involves specific chromatin modifications. The endogenous glial cells, as well as those induced by Gcm overexpression display low levels of histone 3 lysine 9 acetylation (H3K9ac) and Drosophila CREB-binding protein (dCBP) Histone Acetyl-Transferase (HAT). Moreover, we show that dCBP targets the H3K9 residue and that high levels of dCBP HAT disrupt gliogenesis. Thus, glial differentiation needs low levels of histone acetylation, a feature shared by vertebrate glia, calling for an epigenetic pathway conserved in evolution.
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, IGBMC/CNRS/INSERM/UDS, BP 10142, 67404 ILLKIRCH, CU de Strasbourg, France.
authors.forename: Hakima
authors.initials: H
authors.lastname: Flici
authors.forename: Berra
authors.initials: B
authors.lastname: Erkosar
authors.forename: Orban
authors.initials: O
authors.lastname: Komonyi
authors.forename: Omer Faruk
authors.initials: OF
authors.lastname: Karatas
authors.forename: Pietro
authors.initials: P
authors.lastname: Laneve
authors.forename: Angela
authors.initials: A
authors.lastname: Giangrande
mesh_terms: D000107:Acetylation; D000818:Animals; D002454:Cell Differentiation; D002455:Cell Division; D019070:Cell Lineage; D002843:Chromatin / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D029721:Drosophila Proteins / Q000378:metabolism / Q000502:physiology*; D004331:Drosophila melanogaster; D044127:Epigenesis, Genetic; D018507:Gene Expression Regulation, Developmental; D006657:Histones / Q000737:chemistry* / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization; D008938:Mitosis; D058953:Neural Stem Cells / Q000166:cytology*; D009457:Neuroglia / Q000166:cytology*; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014714:Vertebrates / Q000378:metabolism
chemical_list: D002843:Chromatin; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C102805:GCM protein, Drosophila; D006657:Histones; D014157:Transcription Factors