title: Silencing of human DNA polymerase λ causes replication stress and is synthetically lethal with an impaired S phase checkpoint.
abstract: Human DNA polymerase (pol) λ functions in base excision repair and non-homologous end joining. We have previously shown that DNA pol λ is involved in accurate bypass of the two frequent oxidative lesions, 7,8-dihydro-8-oxoguanine and 1,2-dihydro-2-oxoadenine during the S phase. However, nothing is known so far about the relationship of DNA pol λ with the S phase DNA damage response checkpoint. Here, we show that a knockdown of DNA pol λ, but not of its close homologue DNA pol β, results in replication fork stress and activates the S phase checkpoint, slowing S phase progression in different human cancer cell lines. We furthermore show that DNA pol λ protects cells from oxidative DNA damage and also functions in rescuing stalled replication forks. Its absence becomes lethal for a cell when a functional checkpoint is missing, suggesting a DNA synthesis deficiency. Our results provide the first evidence, to our knowledge, that DNA pol λ is required for cell cycle progression and is functionally connected to the S phase DNA damage response machinery in cancer cells.
authors.affiliation: Institute of Molecular Genetics IGM-CNR, via Abbiategrasso 207, I-27100 Pavia, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Zucca
authors.forename: Federica
authors.initials: F
authors.lastname: Bertoletti
authors.forename: Ursula
authors.initials: U
authors.lastname: Wimmer
authors.forename: Elena
authors.initials: E
authors.lastname: Ferrari
authors.forename: Giuliano
authors.initials: G
authors.lastname: Mazzini
authors.forename: Svetlana
authors.initials: S
authors.lastname: Khoronenkova
authors.forename: Nicole
authors.initials: N
authors.lastname: Grosse
authors.forename: Barbara
authors.initials: B
authors.lastname: van Loon
authors.forename: Grigory
authors.initials: G
authors.lastname: Dianov
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hübscher
authors.forename: Giovanni
authors.initials: G
authors.lastname: Maga
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival; D000071877:Checkpoint Kinase 1; D004249:DNA Damage; D019951:DNA Polymerase beta / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D004261:DNA Replication; D006367:HeLa Cells; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D018384:Oxidative Stress; D011494:Protein Kinases / Q000378:metabolism; D034622:RNA Interference; D059767:Recombinational DNA Repair; D059807:S Phase Cell Cycle Checkpoints; D013312:Stress, Physiological / Q000235:genetics
chemical_list: D011494:Protein Kinases; D000071877:Checkpoint Kinase 1; C415367:DNA polymerase beta2; D019951:DNA Polymerase beta; D006918:Hydroxyurea