Sister chromatid exchanges induced by perturbed replication are formed independently of homologous recombination factors

SummarySister chromatid exchanges (SCEs) are products of joint DNA molecule resolution, and are considered to form through homologous recombination (HR). Indeed, upon generation of irradiation-induced DNA breaks, SCE induction was compromised in cells deficient for canonical HR factors BRCA1, BRCA2 and RAD51. Contrarily, replication-blocking agents, including PARP inhibitors, induced SCEs independently of BRCA1, BRCA2 and RAD51. PARP inhibitor-induced SCEs were enriched at common fragile sites (CFSs), and were accompanied by post-replicative single-stranded DNA (ssDNA) gaps. Moreover, PARP inhibitor-induced replication lesions were transmitted into mitosis, suggesting that SCEs originate from mitotic processing of under-replicated DNA. We found that DNA polymerase theta (POLQ) was recruited to mitotic DNA lesions, and loss of POLQ resulted in reduced SCE numbers and severe chromosome fragmentation upon PARP inhibition in HR-deficient cells. Combined, our data show that PARP inhibition generates under-replicated DNA, which is transferred into mitosis and processed into SCEs, independently of canonical HR factors.

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Sister Chromatid Exchanges Are Mediated by Homologous Recombination in Vertebrate Cells

Molecular and Cellular Biology ◽

10.1128/mcb.19.7.5166 ◽

1999 ◽

Vol 19 (7) ◽

pp. 5166-5169 ◽

Cited By ~ 271

Author(s):

Eiichiro Sonoda ◽

Masao S. Sasaki ◽

Ciaran Morrison ◽

Yuko Yamaguchi-Iwai ◽

Minoru Takata ◽

...

Keyword(s):

Homologous Recombination ◽

Sister Chromatid ◽

Sister Chromatid Exchanges ◽

Dna Lesions ◽

End Joining ◽

Chromosomal Stability ◽

Tumorigenic Potential ◽

Associated Proteins ◽

Chromatid Exchanges

ABSTRACT Sister chromatid exchange (SCE) frequency is a commonly used index of chromosomal stability in response to environmental or genetic mutagens. However, the mechanism generating cytologically detectable SCEs and, therefore, their prognostic value for chromosomal stability in mitotic cells remain unclear. We examined the role of the highly conserved homologous recombination (HR) pathway in SCE by measuring SCE levels in HR-defective vertebrate cells. Spontaneous and mitomycin C-induced SCE levels were significantly reduced for chicken DT40 B cells lacking the key HR genes RAD51 and RAD54but not for nonhomologous DNA end-joining (NHEJ)-defectiveKU70 −/− cells. As measured by targeted integration efficiency, reconstitution of HR activity by expression of a human RAD51 transgene restored SCE levels to normal, confirming that HR is the mechanism responsible for SCE. Our findings show that HR uses the nascent sister chromatid to repair potentially lethal DNA lesions accompanying replication, which might explain the lethality or tumorigenic potential associated with defects in HR or HR-associated proteins.

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Low doses of alpha particles do not induce sister chromatid exchanges in bystander Chinese hamster cells defective in homologous recombination

DNA Repair ◽

10.1016/j.dnarep.2007.11.014 ◽

2008 ◽

Vol 7 (3) ◽

pp. 515-522 ◽

Cited By ~ 21

Author(s):

Hatsumi Nagasawa ◽

Paul F. Wilson ◽

David J. Chen ◽

Larry H. Thompson ◽

Joel S. Bedford ◽

...

Keyword(s):

Homologous Recombination ◽

Sister Chromatid ◽

Chinese Hamster ◽

Sister Chromatid Exchanges ◽

Alpha Particles ◽

Low Doses ◽

Chinese Hamster Cells ◽

Chromatid Exchanges

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Increased frequencies of sister chromatid exchanges at common fragile sites (1)(q42) and (19)(q13)

Human Genetics ◽

10.1007/bf00286707 ◽

1989 ◽

Vol 83 (2) ◽

pp. 145-147 ◽

Cited By ~ 14

Author(s):

W. Feichtinger ◽

M. Schmid

Keyword(s):

Sister Chromatid ◽

Sister Chromatid Exchanges ◽

Fragile Sites ◽

Common Fragile Sites ◽

Chromatid Exchanges

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Persistence of DNA lesions and the cytological cancellation of sister chromatid exchanges

Chromosoma ◽

10.1007/bf00327239 ◽

1985 ◽

Vol 92 (1) ◽

pp. 7-10 ◽

Cited By ~ 14

Author(s):

J. B. Schvartzman ◽

V. J. Goyanes ◽

A. Campos ◽

A. M. Lage ◽

C. Veiras ◽

...

Keyword(s):

Sister Chromatid ◽

Sister Chromatid Exchanges ◽

Dna Lesions ◽

Chromatid Exchanges ◽

Persistence Of Dna

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Topoisomerase inhibitors can selectively interfere with different stages of simian virus 40 DNA replication

Molecular and Cellular Biology ◽

10.1128/mcb.6.12.4221-4227.1986 ◽

1986 ◽

Vol 6 (12) ◽

pp. 4221-4227

Author(s):

R M Snapka

Keyword(s):

Dna Replication ◽

Sister Chromatid ◽

Simian Virus 40 ◽

Simian Virus ◽

Sister Chromatid Exchanges ◽

Replication Forks ◽

Dna Breaks ◽

Rapid Reversal ◽

Chromatid Exchanges

I have found that antineoplastic drugs which are known to be inhibitors of mammalian DNA topoisomerases have pronounced and selective effects on simian virus 40 DNA replication. Ellipticine, 4'-(9-acridinylamino)methanesulfon-m-aniside, and Adriamycin blocked decatenation of newly replicated simian virus 40 daughter chromosomes in vivo. The arrested decatenation intermediates produced by these drugs contained single-strand DNA breaks. Ellipticine in particular produced these catenated dimers rapidly and efficiently. Removal of the drug resulted in rapid reversal of the block and completion of decatenation. The demonstration that these drugs interfere with decatenation suggests that they may exert their cytotoxic and antineoplastic effects by preventing the separation of newly replicated cellular chromosomes. Camptothecin rapidly breaks replication forks in growing Cairns structures. It is likely that the target of camptothecin is the "swivel" topoisomerase required for DNA replication and that it is located at or very near the replication fork in vivo. Evidence is presented that many of the broken Cairns structures are in fact half-completed sister chromatid exchanges. One pathway for the resolution of these structures is completion of the sister chromatid exchange to produce a circular head-to-tail dimer.

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