Ash1l methylates Lys36 of histone H3 independently of transcriptional elongation to counteract polycomb silencing.
Molecular mechanisms for the establishment of transcriptional memory are poorly understood. 5,6-dichloro-1-D-ribofuranosyl-benzimidazole (DRB) is a P-TEFb kinase inhibitor that artificially induces the poised RNA polymerase II (RNAPII), thereby manifesting intermediate steps for the establishment of transcriptional activation. Here, using genetics and DRB, we show that mammalian Absent, small, or homeotic discs 1-like (Ash1l), a member of the trithorax group proteins, methylates Lys36 of histone H3 to promote the establishment of Hox gene expression by counteracting Polycomb silencing. Importantly, we found that Ash1l-dependent Lys36 di-, tri-methylation of histone H3 in a coding region and exclusion of Polycomb group proteins occur independently of transcriptional elongation in embryonic stem (ES) cells, although both were previously thought to be consequences of transcription. Genome-wide analyses of histone H3 Lys36 methylation under DRB treatment have suggested that binding of the retinoic acid receptor (RAR) to a certain genomic region promotes trimethylation in the RAR-associated gene independent of its ongoing transcription. Moreover, DRB treatment unveils a parallel response between Lys36 methylation of histone H3 and occupancy of either Tip60 or Mof in a region-dependent manner. We also found that Brg1 is another key player involved in the response. Our results uncover a novel regulatory cascade orchestrated by Ash1l with RAR and provide insights into mechanisms underlying the establishment of the transcriptional activation that counteracts Polycomb silencing.
Division of Molecular Genetics and Epigenetics, Department of Biomolecular Sciences, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga City, Saga, Japan ; Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi City, Saitama, Japan.
Hitomi
H
Miyazaki
Ken
K
Higashimoto
Yukari
Y
Yada
Takaho A
TA
Endo
Jafar
J
Sharif
Toshiharu
T
Komori
Masashi
M
Matsuda
Yoko
Y
Koseki
Manabu
M
Nakayama
Hidenobu
H
Soejima
Hiroshi
H
Handa
Haruhiko
H
Koseki
Susumu
S
Hirose
Kenichi
K
Nishioka
D000818:Animals; D002843:Chromatin / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004004:Dichlororibofuranosylbenzimidazole / Q000494:pharmacology; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster; D020868:Gene Silencing; D051548:Histone Acetyltransferases / Q000378:metabolism; D011495:Histone-Lysine N-Methyltransferase; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000235:genetics; D008745:Methylation; D009687:Nuclear Proteins / Q000378:metabolism; D063146:Polycomb-Group Proteins / Q000235:genetics* / Q000378:metabolism; D042925:Positive Transcriptional Elongation Factor B / Q000037:antagonists & inhibitors / Q000378:metabolism; D012319:RNA Polymerase II / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors / Q000235:genetics* / Q000378:metabolism
D002843:Chromatin; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006657:Histones; D009687:Nuclear Proteins; D063146:Polycomb-Group Proteins; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; D004004:Dichlororibofuranosylbenzimidazole; C490911:ASH1L protein, human; D011495:Histone-Lysine N-Methyltransferase; D051548:Histone Acetyltransferases; C511056:Tip60 protein, Drosophila; C111063:mof protein, Drosophila; D042925:Positive Transcriptional Elongation Factor B; D012319:RNA Polymerase II; D008239:Lysine