title: The histone H4 lysine 20 monomethyl mark, set by PR-Set7 and stabilized by L(3)mbt, is necessary for proper interphase chromatin organization.
abstract: Drosophila PR-Set7 or SET8 is a histone methyltransferase that specifically monomethylates histone H4 lysine 20 (H4K20). L(3)MBT has been identified as a reader of methylated H4K20. It contains several conserved domains including three MBT repeats binding mono- and dimethylated H4K20 peptides. We find that the depletion of PR-Set7 blocks de novo H4K20me1 resulting in the immediate activation of the DNA damage checkpoint, an increase in the size of interphase nuclei, and drastic reduction of cell viability. L(3)mbt on the other hand stabilizes the monomethyl mark, as L(3)mbt-depleted S2 cells show a reduction of more than 60% of bulk monomethylated H4K20 (H4K20me1) while viability is barely affected. Ploidy and basic chromatin structure show only small changes in PR-Set7-depleted cells, but higher order interphase chromatin organization is significantly affected presumably resulting in the activation of the DNA damage checkpoint. In the absence of any other known functions of PR-Set7, the setting of the de novo monomethyl mark appears essential for cell viability in the presence or absence of the DNA damage checkpoint, but once newly assembled chromatin is established the monomethyl mark, protected by L(3)mbt, is dispensable.
authors.affiliation: Waksman Institute, Cancer Institute of New Jersey, Rutgers University, Piscataway, New Jersey, United States of America.
authors.forename: Ayako
authors.initials: A
authors.lastname: Sakaguchi
authors.forename: Eric
authors.initials: E
authors.lastname: Joyce
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Aoki
authors.forename: Paul
authors.initials: P
authors.lastname: Schedl
authors.forename: Ruth
authors.initials: R
authors.lastname: Steward
mesh_terms: D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics; D042002:Chromatin Assembly and Disassembly / Q000502:physiology*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D007399:Interphase / Q000502:physiology*; D008745:Methylation; D009707:Nucleosomes / Q000378:metabolism; D011485:Protein Binding; D055550:Protein Stability; D034622:RNA Interference
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D029721:Drosophila Proteins; D006657:Histones; D009707:Nucleosomes; D011495:Histone-Lysine N-Methyltransferase; C498199:PR-Set7 protein, Drosophila