CCCTC-Binding Factor Meets Poly(ADP-Ribose) Polymerase-1

CCCTC-binding factor (CTCF) is a ubiquitous Zn-finger-containing protein with numerous recognized functions, including, but not limited to, gene activation and repression, enhancer-blocking, X-chromosome inactivation, and gene imprinting. It is believed that the protein performs such a variety of functions by interacting with an array of very diverse proteins. In addition, CTCF undergoes several post-translational modifications, including poly(ADP-ribosyl)ation. The PARylated form of CTCF has recently been implicated in two important functions: gene imprinting and control of ribosomal gene transcription. Here, we summarize and critically discuss the available data on the interplay between CTCF and poly(ADP-ribosyl)ation in these two processes. We consider the newly described phenomena in the broader context of PARP's activities, including the crucial role of protein PARylation in the regulation of the genome methylation pattern.