The dual lives of bidirectional promoters

The sequencing of the human genome led to many insights into gene organization and structure. One interesting observation was the high frequency of bidirectional promoters characterized by two protein encoding genes whose promoters are arranged in a divergent or “head-to-head” configuration with less than 2000 base pairs of intervening sequence. Computational estimates published by various groups indicate that nearly 10% of the coding gene promoters are arranged in such a manner and the extent of this bias is a unique feature of mammalian genomes. Moreover, as a class, head-to-head promoters appear to be enriched in specific categories of gene function. Here we review the structure, composition, genomic properties and functional classifications of genes controlled by bidirectional promoters and explore the biological implication of these features. This article is part of a Special Issue entitled: Chromatin in time and space.

► Bidirectional promoters encompass approximately 10% of the human genome.
► Functional classes cover DNA repair, chromatin stability, maintenance and assembly.
► CtBP binds to multiple transcription factors that target bidirectional promoters.
► CtBP may link bidirectional promoters to multiple epigenetic regulators in cancer.
► CtBP assembly at bidirectional promoters may drive multiple hallmarks of cancer.