R-loops, nucleic acid structures consisting of an RNA-DNA hybrid and displaced single-stranded (ss) DNA, are ubiquitous in organisms from bacteria to mammals. First described in bacteria where they initiate DNA replication, it now appears that R-loops regulate diverse cellular processes such as gene expression, immunoglobulin (Ig) class switching, and DNA repair. Changes in R-loop regulation induce DNA damage and genome instability, and recently it was shown that R-loops are associated with neurodegenerative disorders. We discuss recent developments in the field; in particular, the regulation and effects of R-loops in cells, their effect on genomic and epigenomic stability, and their potential contribution to the origin of diseases including cancer and neurodegenerative disorders.
Keywords: R-loop; epigenomic stability; gene expression; genomic instability.
Copyright © 2015 Elsevier Ltd. All rights reserved.