DOG-1 Is the Caenorhabditis elegans BRIP1/FANCJ Homologue and Functions in Interstrand Cross-Link Repair

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Abstract
Fanconi anemia (FA) is a cancer susceptibility syndrome characterized by defective DNA interstrand cross-link (ICL) repair. Here, we show that DOG-1 is the Caenorhabditis elegans homologue of FANCJ, a helicase mutated in FA-J patients. DOG-1 performs a conserved role in ICL repair, as dog-1 mutants are hypersensitive to ICL-inducing agents, but not to UVC irradiation or X rays. Genetic analysis indicated that dog-1 is epistatic with fcd-2 (C. elegans FANCD2) but is nonepistatic with brc-1 (C. elegans BRCA1), thus establishing the existence of two distinct pathways of ICL repair in worms. Furthermore, DOG-1 is dispensable for FCD-2 and RAD-51 focus formation, suggesting that DOG-1 operates downstream of FCD-2 and RAD-51 in ICL repair. DOG-1 was previously implicated in poly(G)/poly(C) (G/C) tract maintenance during DNA replication. G/C tracts remain stable in the absence of ATL-1, CLK-2 (FA pathway activators), FCD-2, BRC-2, and MLH-1 (associated FA components), implying that DOG-1 is the sole FA component required for G/C tract maintenance in a wild-type background. However, FCD-2 is required to promote deletion-free repair at G/C tracts in dog-1 mutants, consistent with a role for FA factors at the replication fork. The functional conservation between DOG-1 and FANCJ suggests a possible role for FANCJ in G/C tract maintenance in human cells.