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‘Insulator bodies’ are aggregates of proteins but not of insulators
Author(s) -
Golovnin Anton,
Melnikova Larisa,
Volkov Ilya,
Kostuchenko Margarita,
Galkin Alexander V,
Georgiev Pavel
Publication year - 2008
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/embor.2008.32
Subject(s) - biology , insulator (electricity) , chromatin , mutant , genetics , enhancer , microbiology and biotechnology , physics , dna , transcription factor , gene , optoelectronics
Chromatin insulators are thought to restrict the action of enhancers and silencers. The best‐known insulators in Drosophila require proteins such as Suppressor of Hairy wing (Su(Hw)) and Modifier of mdg4 (Mod(mdg4)) to be functional. The insulator‐related proteins apparently colocalize as nuclear speckles in immunostained cells. It has been asserted that these speckles are ‘insulator bodies’ of many Su(Hw)–insulator DNA sites held together by associated proteins, including Mod(mdg4). As we show here using flies, larvae and S2 cells, a mutant Mod(mdg4) protein devoid of the Q‐rich domain supports the function of Su(Hw)‐dependent insulators and efficiently binds to correct insulator sites on the chromosome, but does not form or enter the Su(Hw)‐marked nuclear speckles; conversely, the latter accumulate another (C‐truncated) Mod(mdg4) mutant that cannot interact with Su(Hw) or with the genuine insulators. Hence, it is not the functional genomic insulators but rather aggregated proteins that make the so‐called ‘insulator bodies’.