The MADF-BESS Protein CP60 Is Recruited to Insulators via CP190 and Has Redundant Functions in Drosophila

Abstract

Drosophila CP190 and CP60 are transcription factors that are associated with centrosomes during mitosis. CP190 is an essential transcription factor and preferentially binds to housekeeping gene promoters and insulators through interactions with architectural proteins, including Su(Hw) and dCTCF. CP60 belongs to a family of transcription factors that contain the N-terminal MADF domain and the C-terminal BESS domain, which is characterized by the ability to homodimerize. In this study, we show that the conserved CP60 region adjacent to MADF is responsible for interacting with CP190. In contrast to the well-characterized MADF-BESS transcriptional activator Adf-1, CP60 is recruited to most chromatin sites through its interaction with CP190, and the MADF domain is likely involved in protein–protein interactions but not in DNA binding. The deletion of the Map60 gene showed that CP60 is not an essential protein, despite the strong and ubiquitous expression of CP60 at all stages of Drosophila development. Although CP60 is a stable component of the Su(Hw) insulator complex, the inactivation of CP60 does not affect the enhancer-blocking activity of the Su(Hw)-dependent gypsy insulator. Overall, our results indicate that CP60 has an important but redundant function in transcriptional regulation as a partner of the CP190 protein.

Developmental and Housekeeping Genes: Two Types of Genetic Organization in the Drosophila Genome

“…The insulators discovered in Drosophila [75][76][77] are able to activate target genes ([77-79], (review, [80])). The insulator proteins form associations that bind DNA in varying sites depending on composition of the association of proteins, and CHRIZ/CHROMATOR is a member of this association [81][82][83][84].…”

Development of a New Model System to Study Long-Distance Interactions Supported by Architectural Proteins

“…The CP190 and Mod(mdg4)-67.2 proteins are simultaneously required for the activity of the Su(Hw)-dependent complex and its recruitment to chromatin [44]. Su(Hw)-dependent complexes may also include other proteins, such as HIPP1 [47][48][49][50], CP60 [51,52], and RNA-binding proteins [53][54][55]. Several studies have suggested the participation of the CP190 and Mod(mdg4)-67.2 proteins in maintaining long-distance interactions [56][57][58][59].…”