FANCJ promotes DNA synthesis through G-quadruplex structures

TY - JOUR

T1 - FANCJ promotes DNA synthesis through G-quadruplex structures

AU - Castillo Bosch, Pau

AU - Segura-Bayona, Sandra

AU - Koole, Wouter

AU - van Heteren, Jane T

AU - Dewar, James M

AU - Tijsterman, Marcel

AU - Knipscheer, Puck

N1 - © 2014 The Authors. Published under the terms of the CC BY NC ND 4.0 license.

PY - 2014/11/3

Y1 - 2014/11/3

N2 - 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.

AB - 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.

KW - Animals

KW - Caenorhabditis elegans

KW - Caenorhabditis elegans Proteins

KW - DNA

KW - DNA Helicases

KW - DNA Replication

KW - G-Quadruplexes

KW - Gene Deletion

KW - Humans

KW - Xenopus laevis

U2 - 10.15252/embj.201488663

DO - 10.15252/embj.201488663

M3 - Article

C2 - 25193968

SN - 0261-4189

VL - 33

SP - 2521

EP - 2533

JO - EMBO Journal

JF - EMBO Journal

IS - 21

ER -