The bithorax complex iab-7 Polycomb response element has a novel role in the functioning of the Fab-7 chromatin boundary

• DOI: 10.1371/journal.pgen.1007442
• Publication Date: 2018-08-15T17:24:10Z
• Authors: Olga Kyrchanova; Amina Kurbidaeva; Marat Sabirov; Nikolay Postika; Daniel Wolle; Tsutomu Aoki; Oksana Maksimenko; Vladic Mogila; Paul Schedl; Pavel Georgiev
• Keywords: Male; 0301 basic medicine; Chromatin Immunoprecipitation; Genes, Homeobox; Polycomb-Group Proteins; Genes, Insect; DNA Fragmentation; QH426-470; Response Elements; Chromatin; Epigenesis, Genetic; 03 medical and health sciences; Gene Expression Regulation; Mutation; Genetics; Animals; Drosophila Proteins; Drosophila; Insulator Elements; Research Article

Expression of the three bithorax complex homeotic genes is orchestrated by nine parasegment-specific regulatory domains. Autonomy each domain conferred boundary elements (insulators). Here, we have used an in situ replacement strategy to reanalyze sequences required for functioning one best-characterized fly boundaries, Fab-7. It was initially identified a deletion, Fab-71, that transformed parasegment (PS) 11 into duplicate copy PS12. Fab-71 deleted four nuclease hypersensitive sites, HS*, HS1, HS2, and HS3, located between iab-6 iab-7 Transgenic P-element excision experiments mapped HS*+HS1+HS2, while HS3 shown be Polycomb response element (PRE). Recent showed HS1 both necessary sufficient activity when also present construct. Surprisingly, HS1+HS3 combination has full activity, discovered alone only minimal function. Moreover, combined with distal half dHS1, needed. A ~1,000 kD multiprotein containing GAF protein, called LBC, binds dHS1 sequence show mutations disrupt LBC binding nuclear extracts, eliminate vivo. sites Pho proteins are PRE silencing. In contrast, requires sites. association vivo, depend upon but not Consistent role function dHS1+HS3mPho lost flies heterozygous mutation gene. Taken together, these results reveal novel PREs chromosome architecture.