title: BLM helicase-dependent transport of p53 to sites of stalled DNA replication forks modulates homologous recombination.
abstract: Diverse functions, including DNA replication, recombination and repair, occur during S phase of the eukaryotic cell cycle. It has been proposed that p53 and BLM help regulate these functions. We show that p53 and BLM accumulated after hydroxyurea (HU) treatment, and physically associated and co-localized with each other and with RAD51 at sites of stalled DNA replication forks. HU-induced relocalization of BLM to RAD51 foci was p53 independent. However, BLM was required for efficient localization of either wild-type or mutated (Ser15Ala) p53 to these foci and for physical association of p53 with RAD51. Loss of BLM and p53 function synergistically enhanced homologous recombination frequency, indicating that they mediated the process by complementary pathways. Loss of p53 further enhanced the rate of spontaneous sister chromatid exchange (SCE) in Bloom syndrome (BS) cells, but not in their BLM-corrected counterpart, indicating that involvement of p53 in regulating spontaneous SCE is BLM dependent. These results indicate that p53 and BLM functionally interact during resolution of stalled DNA replication forks and provide insight into the mechanism of genomic fidelity maintenance by these nuclear proteins.
authors.affiliation: Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Sagar
authors.initials: S
authors.lastname: Sengupta
authors.forename: Steven P
authors.initials: SP
authors.lastname: Linke
authors.forename: Remy
authors.initials: R
authors.lastname: Pedeux
authors.forename: Qin
authors.initials: Q
authors.lastname: Yang
authors.forename: Julie
authors.initials: J
authors.lastname: Farnsworth
authors.forename: Susan H
authors.initials: SH
authors.lastname: Garfield
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Valerie
authors.forename: Jerry W
authors.initials: JW
authors.lastname: Shay
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Ellis
authors.forename: Bohdan
authors.initials: B
authors.lastname: Wasylyk
authors.forename: Curtis C
authors.initials: CC
authors.lastname: Harris
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D001816:Bloom Syndrome; D001973:Bromodeoxyuridine / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology; D002460:Cell Line; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006801:Humans; D006918:Hydroxyurea / Q000378:metabolism; D008957:Models, Genetic; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D051135:Rad51 Recombinase; D053484:RecQ Helicases; D011995:Recombination, Genetic; D012694:Serine / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D016159:Tumor Suppressor Protein p53; D012694:Serine; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; D004265:DNA Helicases; D053484:RecQ Helicases; D001973:Bromodeoxyuridine; D006918:Hydroxyurea