title: Heterochromatin protein 1a is required for an open chromatin structure.
abstract: The Drosophila melanogaster fourth chromosome contains interspersed domains of active and repressive chromatin. We investigated a stock harboring a silenced transgene inserted into Dyrk3 and near Caps-two expressed genes on chromosome four. In an HP1a-deficient background, transgene expression was activated while, paradoxically, expression of Dyrk3 and Caps was reduced. We found that the promoters of Dyrk3 and Caps contained DNase I hypersensitive sites but also possessed methylated histone H3 and HP1a, marks of repressive chromatin. In HP1a-deficient flies, the Dyrk3 and Caps promoters displayed diminished accessibility to nuclease digestion, revealing a surprising role for HP1a in opening chromatin.
authors.affiliation: Department of Biochemistry; University of Iowa; Iowa City, IA USA.
authors.forename: Diane E
authors.initials: DE
authors.lastname: Cryderman
authors.forename: Michael W
authors.initials: MW
authors.lastname: Vitalini
authors.forename: Lori L
authors.initials: LL
authors.lastname: Wallrath