Sumoylation of CtIP controls DNA end resection

Abstract

Double strand breaks (DSBs) can be repaired by two major mechanisms. Both ends can be simple re-joined with little or no processing, a mechanism known as non-homologous end-joining. On the other hand, DSBs can be processed and engaged in a more complex repair pathway called homologous recombination (HR). Repair by HR requires a first step called DNA end resection, consisting in the 5' to 3' nucleolitic degradation of one DNA strand at both DNA ends. Resection leads to the appearance of a 3' ssDNA overhang that is immediately coated by the RPA protein complex for protection. The RPA-coated ssDNA is an essential intermediate of all HR subpathways. CtIP is a key protein controlling DNA end resection, but is also involved in other nuclear processes, such as transcription and checkpoint activation. The functional regulation of this protein depends on the interaction with several proteins but also on post-translational modifications.