Functions of Insulators in the Context of Modern Whole-Genome Investigations

Insulators are usually defined as DNA elements with the property to defend the gene from the influence of the other regulatory elements: enhancer-blocking insulators prevent activation of the gene promoter by the enhancer, when located in between them; barrier insulators remove the so-called position-effect variegation, preventing the spread of heterochromatin. In recent years, applications of the whole-genome methods of analysis led to the accumulation of data on the function of insulator elements that go beyond the framework of canonical definitions. This review summarizes the most up-to-date data on the canonical function of insulators in the organization of chromatin architecture and gene transcription and also considers their noncanonical functions supplementing the generally accepted concepts of the role of insulators in the regulation of the genome function.