End resection: a key step in homologous recombination and DNA double-strand break repair

DNA end resection in eukaryotes is a key step in DNA homologous recombination (HR) and HR-mediated DNA double-strand break (DSB) repair, in which DNA2, EXO1 and MRE11 endo- and exonucleases remove several kilobases from the 5′ terminus of the DNA with DSB, while the 3′ terminus remains intact. The end resection-generated 3′ single-stranded DNA (ssDNA) overhang is then coated by RAD51 for subsequent strand invasion. In the last two decades, great progress has been made in understanding the biochemical mechanisms of end resection, including the identification of various enzymes involved in this process. However, some important questions about this process remain to be resolved. In this review, we summarize the general process of end resection and discuss the implications of the most recent findings for understanding of the end resection machinery.