A minimal threshold of FANCJ helicase activity is required for its response to replication stress or double-strand break repair

作者：Bharti Sanjay Kumar; Sommers Joshua A; Awatet Sanket; Bellani Marina A; Khan Irfan; Bradley Lynda; King Graeme A; Seol Yeonee; Vidhyasagar Venkatasubramanian; Wu Yuliang; Abe Takuye; Kobayashi Koji; Shin ya Kazuo; Kitao Hiroyuki; Wold Marc S; Branzei Dana; Neuman Keir C; Brosh Robert M Jr^*

来源：Nucleic Acids Research, 2018, 46(12): 6238-6256.

DOI：10.1093/nar/gky403

Fanconi Anemia (FA) is characterized by bone marrow failure, congenital abnormalities, and cancer. Of over 20 FA-linked genes, FANCJ uniquely encodes a DNA helicase andmutations are also associated with breast and ovarian cancer. fancj(-/-) cells are sensitive to DNA interstrand cross-linking (ICL) and replication fork stalling drugs. We delineated the molecular defects of two FA patient-derived FANCJ helicase domain mutations. FANCJ-R707C was compromised in dimerization and helicase processivity, whereas DNA unwinding by FANCJ-H396D was barely detectable. DNA binding and ATP hydrolysis was defective for both FANCJ-R707C and FANCJ-H396D, the latter showing greater reduction. Expression of FANCJ-R707C or FANCJ-H396D in fancj(-/-) cells failed to rescue cisplatin or mitomycin sensitivity. Live-cell imaging demonstrated a significantly compromised recruitment of FANCJ-R707C to laser-induced DNA damage. However, FANCJ-R707C expressed in fancj(-/-) cells conferred resistance to the DNA polymerase inhibitor aphidicolin, G-quadruplex ligand telomestatin, or DNA strand-breaker bleomycin, whereas FANCJ-H396D failed. Thus, a minimal threshold of FANCJ catalytic activity is required to overcome replication stress induced by aphidicolin or telomestatin, or to repair bleomycin-induced DNA breakage. These findings have implications for therapeutic strategies relying on DNA cross-link sensitivity or heightened replication stress characteristic of cancer cells.

• 出版日期2018-7-6