A CAF-1 dependent pool of HP1 during heterochromatin duplication.
To investigate how the complex organization of heterochromatin is reproduced at each replication cycle, we examined the fate of HP1-rich pericentric domains in mouse cells. We find that replication occurs mainly at the surface of these domains where both PCNA and chromatin assembly factor 1 (CAF-1) are located. Pulse-chase experiments combined with high-resolution analysis and 3D modeling show that within 90 min newly replicated DNA become internalized inside the domain. Remarkably, during this time period, a specific subset of HP1 molecules (alpha and gamma) coinciding with CAF-1 and replicative sites is resistant to RNase treatment. Furthermore, these replication-associated HP1 molecules are detected in Suv39 knockout cells, which otherwise lack stable HP1 staining at pericentric heterochromatin. This replicative pool of HP1 molecules disappears completely following p150CAF-1 siRNA treatment. We conclude that during replication, the interaction of HP1 with p150CAF-1 is essential to promote delivery of HP1 molecules to heterochromatic sites, where they are subsequently retained by further interactions with methylated H3-K9 and RNA.
Quivy
Jean-Pierre
JP
Institut Curie, Section de Recherche, UMR218 du CNRS, 26, Paris, France.
Roche
Danièle
D
Kirschner
Doris
D
Tagami
Hideaki
H
Nakatani
Yoshihiro
Y
Almouzni
Geneviève
G
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D056504:Chromatin Assembly Factor-1; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006570:Heterochromatin / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008780:Methyltransferases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism
C533593:CHAF1B protein, human; D056504:Chromatin Assembly Factor-1; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D006570:Heterochromatin; D006657:Histones; D018809:Proliferating Cell Nuclear Antigen; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D012097:Repressor Proteins; D000090266:Chromobox Protein Homolog 5; C407843:SUV39H1 protein, human; C498700:Suv39h1 protein, mouse; D008780:Methyltransferases; D012260:Ribonucleases