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Shieldin – the protector of DNA ends
Author(s) -
Setiaputra Dheva,
Durocher Daniel
Publication year - 2019
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.15252/embr.201847560
Subject(s) - dna , chemistry , biology , microbiology and biotechnology , biochemistry
DNA double‐strand breaks are a threat to genome integrity and cell viability. The nucleolytic processing of broken DNA ends plays a central role in dictating the repair processes that will mend these lesions. Usually, DNA end resection promotes repair by homologous recombination, whereas minimally processed ends are repaired by non‐homologous end joining. Important in this process is the chromatin‐binding protein 53 BP 1, which inhibits DNA end resection. How 53 BP 1 shields DNA ends from nucleases has been an enduring mystery. The recent discovery of shieldin, a four‐subunit protein complex with single‐stranded DNA ‐binding activity, illuminated a strong candidate for the ultimate effector of 53 BP 1‐dependent end protection. Shieldin consists of REV 7, a known 53 BP 1‐pathway component, and three hitherto uncharacterized proteins: C20orf196 ( SHLD 1), FAM 35A ( SHLD 2), and CTC ‐534A2.2 ( SHLD 3). Shieldin promotes many 53 BP 1‐associated activities, such as the protection of DNA ends, non‐homologous end joining, and immunoglobulin class switching. This review summarizes the identification of shieldin and the various models of shieldin action and highlights some outstanding questions requiring answers to gain a full molecular understanding of shieldin function.