title: Mutant genetic background affects the functional rearrangement and kinetic properties of JMJD2b histone demethylase.
abstract: We have studied JMJD2b histone demethylase, which antagonizes H3K9me3 in the pericentromeric heterochromatin. In cells with a deficiency in the histone methyltransferase SUV39h, the level of full-length JMJD2b (JMJD2b-GFP-1086) at chromocenters was reduced, corresponding to a global decrease in JMJD2b and H3K9me3. In wild-type fibroblasts, the chromatin of ribosomal genes, which is dense with H3K9 methylation, lacked JMJD2b-GFP-1086, while mutant and truncated forms of JMJD2b densely occupied the nucleolar compartment. This implies that the PHD Zn-fingers and Tudor domains, which were removed in truncated JMJD2b, are responsible for the aberrant JMJD2b function. Intriguingly, the JMJD2b-GFP-1086 level was significantly higher in tumor cell nucleoli. The kinetic properties of JMJD2b-GFP-1086 in the nucleoli and nucleoplasm of normal and tumor cells were similar; ∼50% recovery of prebleached intensity was reached after <1 s. However, the mobile fraction of JMJD2b-GFP-1086 was increased in SUV39h-deficient cells. Similarly, the mobile fractions of mutant JMJD2b(1-424)H189A-GFP and truncated JMJD2b(1-424)GFP were greater than that measured for the full-length protein. We suggest that nucleoli are the site of an aberrant function of JMJD2b, the kinetic properties of which can be influenced by a mutant genetic background.
authors.affiliation: Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, CZ-612 65 Brno, Czech Republic. bartova@ibp.cz
authors.forename: Eva
authors.initials: E
authors.lastname: Bártová
authors.forename: Lenka
authors.initials: L
authors.lastname: Stixová
authors.forename: Gabriela
authors.initials: G
authors.lastname: Galiová
authors.forename: Andrea
authors.initials: A
authors.lastname: Harničarová Horáková
authors.forename: Soňa
authors.initials: S
authors.lastname: Legartová
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kozubek
mesh_terms: D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000235:genetics / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D004275:DNA, Ribosomal / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D015321:Gene Rearrangement; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics; D006801:Humans; D056484:Jumonji Domain-Containing Histone Demethylases / Q000235:genetics* / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D009154:Mutation; D012270:Ribosomes / Q000378:metabolism; D016335:Zinc Fingers
chemical_list: D002843:Chromatin; D004275:DNA, Ribosomal; D056484:Jumonji Domain-Containing Histone Demethylases; D000076983:Histone Methyltransferases; D011495:Histone-Lysine N-Methyltransferase