Study of dCTCF Insulator Activity in Drosophilamelanogaster Model Systems.

Using transgenic Drosophila model systems, we showed that four binding sites for the architectural protein dCTCF per se cannot form an effective insulator that blocks enhancers and protects against the Polycomb-dependent repression. These results suggest that, in the known Drosophila insulators, the dCTCF protein functions in cooperation with other architectural proteins.

Functional role of dimerization and CP190 interacting domains of CTCF protein in Drosophila melanogaster.

Background: Insulators play a central role in gene regulation, chromosomal architecture and genome function in higher eukaryotes. To learn more about how insulators carry out their diverse functions, we have begun an analysis of the Drosophila CTCF (dCTCF). CTCF is one of the few insulator proteins known to be conserved from flies to man.

Effective blocking of the white enhancer requires cooperation between two main mechanisms suggested for the insulator function.

Chromatin insulators block the action of transcriptional enhancers when interposed between an enhancer and a promoter. In this study, we examined the role of chromatin loops formed by two unrelated insulators, gypsy and Fab-7, in their enhancer-blocking activity. To test for this activity, we selected the white reporter gene that is activated by the eye-specific enhancer.

Selective interactions of boundaries with upstream region of Abd-B promoter in Drosophila bithorax complex and role of dCTCF in this process.

Expression of the genes Ubx, abd-A, and Abd-B of the bithorax complex depends on its cis-regulatory region, which is divided into discrete functional domains (iab). Boundary/insulator elements, named Mcp, Fab-6, Fab-7 and Fab-8 (PTS/F8), have been identified at the borders of the iab domains. Recently, binding sites for a Drosophila homolog of the vertebrate insulator protein CTCF have been identified in Mcp, Fab-6 and Fab-8 and also in several regions that correspond to predicted boundaries, Fab-3 and Fab-4 in particular.