title: ATR phosphorylates SMARCAL1 to prevent replication fork collapse.
abstract: The DNA damage response kinase ataxia telangiectasia and Rad3-related (ATR) coordinates much of the cellular response to replication stress. The exact mechanisms by which ATR regulates DNA synthesis in conditions of replication stress are largely unknown, but this activity is critical for the viability and proliferation of cancer cells, making ATR a potential therapeutic target. Here we use selective ATR inhibitors to demonstrate that acute inhibition of ATR kinase activity yields rapid cell lethality, disrupts the timing of replication initiation, slows replication elongation, and induces fork collapse. We define the mechanism of this fork collapse, which includes SLX4-dependent cleavage yielding double-strand breaks and CtIP-dependent resection generating excess single-stranded template and nascent DNA strands. Our data suggest that the DNA substrates of these nucleases are generated at least in part by the SMARCAL1 DNA translocase. Properly regulated SMARCAL1 promotes stalled fork repair and restart; however, unregulated SMARCAL1 contributes to fork collapse when ATR is inactivated in both mammalian and Xenopus systems. ATR phosphorylates SMARCAL1 on S652, thereby limiting its fork regression activities and preventing aberrant fork processing. Thus, phosphorylation of SMARCAL1 is one mechanism by which ATR prevents fork collapse, promotes the completion of DNA replication, and maintains genome integrity.
authors.affiliation: Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
authors.forename: Frank B
authors.initials: FB
authors.lastname: Couch
authors.forename: Carol E
authors.initials: CE
authors.lastname: Bansbach
authors.forename: Robert
authors.initials: R
authors.lastname: Driscoll
authors.forename: Jessica W
authors.initials: JW
authors.lastname: Luzwick
authors.forename: Gloria G
authors.initials: GG
authors.lastname: Glick
authors.forename: Rémy
authors.initials: R
authors.lastname: Bétous
authors.forename: Clinton M
authors.initials: CM
authors.lastname: Carroll
authors.forename: Sung Yun
authors.initials: SY
authors.lastname: Jung
authors.forename: Jun
authors.initials: J
authors.lastname: Qin
authors.forename: Karlene A
authors.initials: KA
authors.lastname: Cimprich
authors.forename: David
authors.initials: D
authors.lastname: Cortez
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication / Q000187:drug effects / Q000502:physiology*; D004277:DNA, Single-Stranded / Q000235:genetics; D004789:Enzyme Activation; D006801:Humans; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D014981:Xenopus
chemical_list: D018797:Cell Cycle Proteins; D004277:DNA, Single-Stranded; D047428:Protein Kinase Inhibitors; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; C412482:SMARCAL1 protein, human; D004265:DNA Helicases
keywords: ATR; DNA damage response; DNA replication; HARP; SMARCAL1; cell cycle checkpoint