CTCF, cohesin, and histone variants: connecting the genome

During the last decades our view of the genome organization has changed. We moved from a linear view to a looped view of the genome. It is now well established that inter- and intra-connections occur between chromosomes and play a major role in gene regulations. These interconnections are mainly orchestrated by the CTCF protein, which is also known as the "master weaver" of the genome. Recent advances in sequencing and genome-wide studies revealed that CTCF binds to DNA at thousands of sites within the human genome, providing the possibility to form thousands of genomic connection hubs. Strikingly, two histone variants, namely H2A.Z and H3.3, strongly co-localize at CTCF binding sites. In this article, we will review the recent advances in CTCF biology and discuss the role of histone variants H2A.Z and H3.3 at CTCF binding sites.