title: FANCJ promotes DNA synthesis through G-quadruplex structures.
abstract: Our genome contains many G-rich sequences, which have the propensity to fold into stable secondary DNA structures called G4 or G-quadruplex structures. These structures have been implicated in cellular processes such as gene regulation and telomere maintenance. However, G4 sequences are prone to mutations particularly upon replication stress or in the absence of specific helicases. To investigate how G-quadruplex structures are resolved during DNA replication, we developed a model system using ssDNA templates and Xenopus egg extracts that recapitulates eukaryotic G4 replication. Here, we show that G-quadruplex structures form a barrier for DNA replication. Nascent strand synthesis is blocked at one or two nucleotides from the G4. After transient stalling, G-quadruplexes are efficiently unwound and replicated. In contrast, depletion of the FANCJ/BRIP1 helicase causes persistent replication stalling at G-quadruplex structures, demonstrating a vital role for this helicase in resolving these structures. FANCJ performs this function independently of the classical Fanconi anemia pathway. These data provide evidence that the G4 sequence instability in FANCJ(-/-) cells and Fancj/dog1 deficient C. elegans is caused by replication stalling at G-quadruplexes.
authors.affiliation: Hubrecht Institute-KNAW, University Medical Center Utrecht & Cancer GenomiCs Netherlands, Utrecht, The Netherlands.
authors.forename: Pau
authors.initials: P
authors.lastname: Castillo Bosch
authors.affiliation: Hubrecht Institute-KNAW, University Medical Center Utrecht & Cancer GenomiCs Netherlands, Utrecht, The Netherlands.
authors.forename: Sandra
authors.initials: S
authors.lastname: Segura-Bayona
authors.affiliation: Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Wouter
authors.initials: W
authors.lastname: Koole
authors.affiliation: Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Jane T
authors.initials: JT
authors.lastname: van Heteren
authors.affiliation: Harvard Medical School, Boston, MA, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: Dewar
authors.affiliation: Leiden University Medical Center, Leiden, The Netherlands m.tijsterman@lumc.nl p.knipscheer@hubrecht.eu.
authors.forename: Marcel
authors.initials: M
authors.lastname: Tijsterman
authors.affiliation: Hubrecht Institute-KNAW, University Medical Center Utrecht & Cancer GenomiCs Netherlands, Utrecht, The Netherlands m.tijsterman@lumc.nl p.knipscheer@hubrecht.eu.
authors.forename: Puck
authors.initials: P
authors.lastname: Knipscheer
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D004247:DNA / Q000096:biosynthesis*; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication / Q000502:physiology*; D054856:G-Quadruplexes; D017353:Gene Deletion; D006801:Humans; D014982:Xenopus laevis
chemical_list: D029742:Caenorhabditis elegans Proteins; D004247:DNA; D004265:DNA Helicases; C464789:Dog-1 protein, C elegans
keywords: DNA Replication; FANCJ; G4 DNA; G‐quadruplex; Xenopus egg extract