Neddylation inhibits CtIP-mediated resection and regulates DNA double strand break repair pathway choice

Abstract

DNA double strand breaks are the most cytotoxic lesions that can occur on the DNA. They can be repaired by different mechanisms and optimal survival requires a tight control between them. Here we uncover protein deneddylation as a major controller of repair pathway choice. Neddylation inhibition changes the normal repair profile toward an increase on homologous recombination. Indeed, RNF111/UBE2M-mediated neddylation acts as an inhibitor of BRCA1 and CtIP-mediated DNA end resection, a key process in repair pathway choice. By controlling the length of ssDNA produced during DNA resection, protein neddylation not only affects the choice between NHEJ and homologous recombination but also controls the balance between different recombination subpathways. Thus, protein neddylation status has a great impact in the way cells respond to DNA breaks.

CtIP: A DNA damage response protein at the intersection of DNA metabolism

“…Phospho-dependent Pin1-mediated proline isomerization of CtIP was also shown to promote the ubiquitination of CtIP and subsequent degradation [42], and BRCA1 can also ubiquitinate CtIP in vitro; the ubiquitinated form of the protein was not degraded in this case but shown to associate more efficiently with chromatin [43]. NEDDylation has also been shown to modulate interaction between BRCA1 and CtIP, thus, altering short-and long-range resection profiles [56]; however, it is not clear whether NEDDylation does so by altering phosphorylation of the S327 site, which is implicated in CtIP-BRCA1 interaction, or by obstructing binding through another mechanism.…”

“…CtIP is also acetylated, ubiquitinated, and NEDDylated [41,43,56,57]. De-acetylation of K432, K526, and K602CtIP residues by Sirt6 plays a critical role in response to DNA damage by promoting recruitment of CtIP to chromatin [41].…”

Repair Pathway Choices and Consequences at the Double-Strand Break

“…These include Sae2, Mre11, Sgs1, and Exo1 in yeast, and BLM and CtIP in human cells [21,23]. A recent study has revealed that RNF111/UBE2M-mediated neddylation acts as an inhibitor of BRCA1 and CtIP-mediated DNA end resection [24]. Additionally, BRCA1, which forms a complex with CtIP and the MRN complex (MRE11, RAD50, and NBS1), and thus plays a crucial role in promoting DSB end resection [25], has been shown to be modified through polyribosylation by PARP1, which has been suggested to play key roles in regulating HR levels [26].…”

How cells ensure correct repair of DNA double-strand breaks

“…The E3 ubiquitin ligase, CRL3 KLHL15 , targets CtIP for proteasomal degradation (33). CtIP activity also appears to be limited by RNF111-mediated neddylation, although CtIP is not a direct substrate for RNF111 (34). In each of these cases, the exact mechanism by which KLHL15 levels or RNF111 activity are regulated in response to DNA damage to modulate CtIP activity has yet to be fully understood.…”