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Mutations in DONSON disrupt replication fork stability and cause microcephalic dwarfism.

AUTHORS

Reynolds JJJohn J , Bicknell LS Louise S , Carroll P Paula , Higgs MR Martin R , Shaheen R Ranad , Murray JE Jennie E , Papadopoulos DK Dimitrios K , Leitch A Andrea , Murina O Olga , Tarnauskaitė Ž Žygimantė , Wessel SR Sarah R , Zlatanou A Anastasia , Vernet A Audrey , von Kriegsheim A Alex , Mottram RM Rachel M A , Logan CV Clare V , Bye H Hannah , Li Y Yun , Brean A Alexander , Maddirevula S Sateesh , Challis RC Rachel C , Skouloudaki K Kassiani , Almoisheer A Agaadir , Alsaif HS Hessa S , Amar A Ariella , Prescott NJ Natalie J , Bober MB Michael B , Duker A Angela , Faqeih E Eissa , Seidahmed MZ Mohammed Zain , Al Tala S Saeed , Alswaid A Abdulrahman , Ahmed S Saleem , Al-Aama JY Jumana Yousuf , Altmüller J Janine , Al Balwi M Mohammed , Brady AF Angela F , Chessa L Luciana , Cox H Helen , Fischetto R Rita , Heller R Raoul , Henderson BD Bertram D , Hobson E Emma , Nürnberg P Peter , Percin EF E Ferda , Peron A Angela , Spaccini L Luigina , Quigley AJ Alan J , Thakur S Seema , Wise CA Carol A , Yoon G Grace , Alnemer M Maha , Tomancak P Pavel , Yigit G Gökhan , Taylor AM A Malcolm R , Reijns MA Martin A M , Simpson MA Michael A , Cortez D David , Alkuraya FS Fowzan S , Mathew CG Christopher G , Jackson AP Andrew P , Stewart GS Grant S . Nature genetics. 2017 2 13; ().

ABSTRACT

To ensure efficient genome duplication, cells have evolved numerous factors that promote unperturbed DNA replication and protect, repair and restart damaged forks. Here we identify downstream neighbor of SON (DONSON) as a novel fork protection factor and report biallelic DONSON mutations in 29 individuals with microcephalic dwarfism. We demonstrate that DONSON is a replisome component that stabilizes forks during genome replication. Loss of DONSON leads to severe replication-associated DNA damage arising from nucleolytic cleavage of stalled replication forks. Furthermore, ATM- and Rad3-related (ATR)-dependent signaling in response to replication stress is impaired in DONSON-deficient cells, resulting in decreased checkpoint activity and the potentiation of chromosomal instability. Hypomorphic mutations in DONSON substantially reduce DONSON protein levels and impair fork stability in cells from patients, consistent with defective DNA replication underlying the disease phenotype. In summary, we have identified mutations in DONSON as a common cause of microcephalic dwarfism and established DONSON as a critical replication fork protein required for mammalian DNA replication and genome stability.

To ensure efficient genome duplication, cells have evolved numerous factors that promote unperturbed DNA replication and protect, repair and restart damaged forks. Here we identify downstream neighbor of SON (DONSON) as a novel fork protection factor and report biallelic DONSON mutations in 29 individuals with microcephalic dwarfism. We demonstrate that DONSON is a replisome component that stabilizes forks during genome replication. Loss of DONSON leads to severe replication-associated DNA damage arising from nucleolytic cleavage of stalled replication forks. Furthermore, ATM- and Rad3-related (ATR)-dependent signaling in response to replication stress is impaired in DONSON-deficient cells, resulting in decreased checkpoint activity and the potentiation of chromosomal instability. Hypomorphic mutations in DONSON substantially reduce DONSON protein levels and impair fork stability in cells from patients, consistent with defective DNA replication underlying the disease phenotype. In summary, we have identified mutations in DONSON as a common cause of microcephalic dwarfism and established DONSON as a critical replication fork protein required for mammalian DNA replication and genome stability.

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