title: Structural differences in centromeric heterochromatin are spatially reconciled on fertilisation in the mouse zygote.
abstract: In mammals, paternal and maternal pronuclei undergo profound chromatin reorganisation upon fertilisation. How these events are orchestrated within centromeric regions to ensure proper chromosome segregation in the following cellular divisions is unknown. In this study, we followed the dynamic unfolding of the centromeric regions, i.e. the centric and pericentric satellite repeats, by DNA fluorescent in situ hybridization (FISH) during the first cell cycle up to the two-cell stage. The distinct chromatin from female and male gametes both undergo rapid remodelling and reach a zygotic organisation in which the satellites occupy restricted spatial domains surrounding the nucleolar precursor body. A transition from this zygotic to a somatic cell-like organisation takes place during the two-cell stage. Using 3D immuno-FISH, we find that, whereas maternal pericentric regions are marked with H3K9me3, H4K20me3 and HP1beta, paternal ones only showed HP1beta marking. Thus, despite different chromatin features, male and female pronuclei organise their centromeric regions in the same way within the nuclei to align chromosomes on the metaphase plate and segregate them appropriately. Our findings highlight the importance of ensuring a proper centromere function while preserving the distinction of parental genome origin during the return to totipotency in the zygote.
authors: Laboratory of Nuclear Dynamics and Nuclear Plasticity, UMR218 CNRS/Institut Curie, 75248, Paris Cedex 05, France.
authors: Aline V
authors: AV
authors: Probst
authors: Fátima
authors: F
authors: Santos
authors: Wolf
authors: W
authors: Reik
authors: Geneviève
authors: G
authors: Almouzni
authors: Wendy
authors: W
authors: Dean
mesh_terms: D000818:Animals; D002503:Centromere / Q000737:chemistry* / Q000648:ultrastructure; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000302:isolation & purification; D004247:DNA / Q000032:analysis / Q000737:chemistry; D005260:Female; D005306:Fertilization; D006570:Heterochromatin / Q000737:chemistry* / Q000648:ultrastructure; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D051379:Mice; D015053:Zygote / Q000737:chemistry* / Q000166:cytology
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D006570:Heterochromatin; D004247:DNA