Heterochromatin formation in the mouse embryo requires critical residues of the histone variant H3.3.
In mammals, oocyte fertilization by sperm initiates development. This is followed by epigenetic reprogramming of both parental genomes, which involves the de novo establishment of chromatin domains. In the mouse embryo, methylation of histone H3 establishes an epigenetic asymmetry and is predominant in the maternal pronucleus. However, the roles of differential incorporation of histone H3 variants in the parental chromatin, and of modified residues within specific histone variants, have not been addressed. Here we show that the histone variant H3.3, and in particular lysine 27, is required for the establishment of heterochromatin in the mouse embryo. H3.3 localizes to paternal pericentromeric chromatin during S phase at the time of transcription of pericentromeric repeats. Mutation of H3.3 K27, but not of H3.1 K27, results in aberrant accumulation of pericentromeric transcripts, HP1 mislocalization, dysfunctional chromosome segregation and developmental arrest. This phenotype is rescued by injection of double-stranded RNA (dsRNA) derived from pericentromeric transcripts, indicating a functional link between H3.3K27 and the silencing of such regions by means of an RNA-interference (RNAi) pathway. Our work demonstrates a role for a modifiable residue within a histone-variant-specific context during reprogramming and identifies a novel function for mammalian H3.3 in the initial formation of dsRNA-dependent heterochromatin.
Santenard
Angèle
A
Institut de Génétique et de Biologie Moléculaire et Cellulaire, Centre national de la recherche scientifique/Institut National de la Santé et de la Recherche Médicale U964, Université de Strasbourg, F-67404 Illkirch, France.
Ziegler-Birling
Céline
C
Koch
Marc
M
Tora
Làszlò
L
Bannister
Andrew J
AJ
Torres-Padilla
Maria-Elena
ME
D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D020090:Chromosome Segregation / Q000235:genetics; D004276:DNA, Satellite / Q000235:genetics; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism*; D047108:Embryonic Development / Q000235:genetics; D044127:Epigenesis, Genetic / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D006570:Heterochromatin / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000235:genetics* / Q000378:metabolism*; D008239:Lysine / Q000235:genetics; D008297:Male; D008745:Methylation; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D012330:RNA, Double-Stranded / Q000008:administration & dosage / Q000235:genetics; D012333:RNA, Messenger / Q000008:administration & dosage / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D015053:Zygote / Q000166:cytology / Q000378:metabolism
C096188:Cbx1 protein, mouse; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004276:DNA, Satellite; D006570:Heterochromatin; D006657:Histones; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D008239:Lysine