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

Abstract

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 and mutations 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.

• Authors: Sanjay Kumar Bharti, Joshua A Sommers, Sanket Awate, Marina A Bellani, Irfan Khan, Lynda Bradley, Graeme A King, Yeonee Seol, Venkatasubramanian Vidhyasagar, Yuliang Wu, Takuye Abe, Koji Kobayashi, Kazuo Shin-Ya, Hiroyuki Kitao, Marc S Wold, Dana Branzei, Keir C Neuman, Robert M Brosh Jr
• Journal: Nucleic acids research (Nucleic Acids Res) Vol. 46 Issue 12 Pg. 6238-6256 (07 06 2018) ISSN: 1362-4962 [Electronic] England
• PMID: 29788478 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• DNA, Single-Stranded
• Fanconi Anemia Complementation Group Proteins
• Oxazoles
• Recombinases
• Replication Protein A
• telomestatin
• Aphidicolin
• Checkpoint Kinase 1
• Rad51 Recombinase
• Adenosine Triphosphatases
• DNA Helicases
• BRIP1 protein, human
• RNA Helicases
• Cisplatin

Topics

• Adenosine Triphosphatases (genetics, metabolism)
• Animals
• Aphidicolin (toxicity)
• Cell Line
• Checkpoint Kinase 1 (metabolism)
• Chickens
• Cisplatin (toxicity)
• DNA Breaks, Double-Stranded
• DNA Helicases (genetics, metabolism)
• DNA Repair
• DNA Replication
• DNA, Single-Stranded
• Fanconi Anemia (genetics)
• Fanconi Anemia Complementation Group Proteins (chemistry, genetics, metabolism)
• G-Quadruplexes
• Mutation, Missense
• Oxazoles (toxicity)
• RNA Helicases (chemistry, genetics, metabolism)
• Rad51 Recombinase (analysis)
• Recombinases (genetics, metabolism)
• Replication Protein A (metabolism)
• Stress, Physiological