title: Distinct functions of human RECQ helicases WRN and BLM in replication fork recovery and progression after hydroxyurea-induced stalling.
abstract: Human WRN and BLM genes are members of the conserved RECQ helicase family. Mutations in these genes are associated with Werner and Bloom syndromes. WRN and BLM proteins are implicated in DNA replication, recombination, repair, telomere maintenance, and transcription. Using microfluidics-assisted display of DNA for replication track analysis (ma-RTA), we show that WRN and BLM contribute additively to normal replication fork progression, and non-additively, in a RAD51-dependent pathway, to resumption of replication after arrest by hydroxyurea (HU), a replication-stalling drug. WRN but not BLM is required to support fork progression after HU. Resumption of replication by forks may be necessary but is not sufficient for timely completion of the cell cycle after HU arrest, as depletion of WRN or BLM compromises fork recovery to a similar degree, but only BLM depletion leads to extensive delay of cell division after HU, as well as more pronounced chromatin bridging. Finally, we show that recovery from HU includes apparent removal of some of the DNA that was synthesized immediately after release from HU, a novel phenomenon that we refer to as nascent strand processing, NSP.
authors.affiliation: Department of Pathology, University of Washington, Seattle, WA 98195-7705, United States. julias@u.washington.edu
authors.forename: Julia M
authors.initials: JM
authors.lastname: Sidorova
authors.forename: Keffy
authors.initials: K
authors.lastname: Kehrli
authors.forename: Frances
authors.initials: F
authors.lastname: Mao
authors.forename: Raymond
authors.initials: R
authors.lastname: Monnat
mesh_terms: D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D002843:Chromatin / Q000187:drug effects; D004261:DNA Replication / Q000187:drug effects / Q000235:genetics*; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D006801:Humans; D006918:Hydroxyurea / Q000633:toxicity; D044085:Microfluidics; D051135:Rad51 Recombinase / Q000378:metabolism; D053484:RecQ Helicases / Q000378:metabolism*; D000071657:Werner Syndrome Helicase
chemical_list: D002843:Chromatin; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D005090:Exodeoxyribonucleases; C097151:Bloom syndrome protein; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase; D006918:Hydroxyurea