title: PERK inhibits DNA replication during the Unfolded Protein Response via Claspin and Chk1.
abstract: Stresses such as hypoxia, nutrient deprivation and acidification disturb protein folding in the endoplasmic reticulum (ER) and activate the Unfolded Protein Response (UPR) to trigger adaptive responses through the effectors, PERK, IRE1 and ATF6. Most of these responses relate to ER homoeostasis; however, here we show that the PERK branch of the UPR also controls DNA replication. Treatment of cells with the non-genotoxic UPR agonist thapsigargin led to a rapid inhibition of DNA synthesis that was attributable to a combination of DNA replication fork slowing and reduced replication origin firing. DNA synthesis inhibition was dependent on the UPR effector PERK and was associated with phosphorylation of the checkpoint adaptor protein Claspin and activation of the Chk1 effector kinase, both of which occurred in the absence of detectable DNA damage. Remarkably, thapsigargin did not inhibit bulk DNA synthesis or activate Chk1 in cells depleted of Claspin, or when Chk1 was depleted or subject to chemical inhibition. In each case thapsigargin-resistant DNA synthesis was due to an increase in replication origin firing that compensated for reduced fork progression. Taken together, our results unveil a new aspect of PERK function and previously unknown roles for Claspin and Chk1 as negative regulators of DNA replication in the absence of genotoxic stress. Because tumour cells proliferate in suboptimal environments, and frequently show evidence of UPR activation, this pathway could modulate the response to DNA replication-targeted chemotherapies.
authors.affiliation: Unidad de Investigación, Hospital Universitario de Canarias, Instituto de Tecnologías Biomédicas, Ofra s/n, La Cuesta, La Laguna, Tenerife, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Cabrera
authors.affiliation: Unidad de Investigación, Hospital Universitario de Canarias, Instituto de Tecnologías Biomédicas, Ofra s/n, La Cuesta, La Laguna, Tenerife, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Hernández-Pérez
authors.affiliation: Institut Curie, Centre de Recherche, CNRS-UMR 3244, Paris Cedex 05, France.|Sorbonne Universités, UPMC Univ Paris 06, Paris, France.|CNRS-UMR 3244, Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: Koundrioukoff
authors.affiliation: Institut Curie, Centre de Recherche, CNRS-UMR 3244, Paris Cedex 05, France.|Sorbonne Universités, UPMC Univ Paris 06, Paris, France.|CNRS-UMR 3244, Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Debatisse
authors.affiliation: Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA.
authors.forename: D
authors.initials: D
authors.lastname: Kim
authors.affiliation: Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Smolka
authors.affiliation: Unidad de Investigación, Hospital Universitario de Canarias, Instituto de Tecnologías Biomédicas, Ofra s/n, La Cuesta, La Laguna, Tenerife, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Freire
authors.affiliation: Instituto de Tecnologías Biomédicas, Centro de Investigaciones Biomédicas de Canarias, Facultad de Medicina, Campus Ciencias de la Salud, Universidad de La Laguna, La Laguna, Tenerife, Spain.
authors.forename: D A
authors.initials: DA
authors.lastname: Gillespie
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1 / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication / Q000502:physiology*; D006801:Humans; D014162:Transfection; D056811:Unfolded Protein Response / Q000502:physiology*; D019892:eIF-2 Kinase / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C488158:CLSPN protein, human; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C460640:EIF2AK3 protein, human; D019892:eIF-2 Kinase