title: JAK2V617F promotes replication fork stalling with disease-restricted impairment of the intra-S checkpoint response.
abstract: Cancers result from the accumulation of genetic lesions, but the cellular consequences of driver mutations remain unclear, especially during the earliest stages of malignancy. The V617F mutation in the JAK2 non-receptor tyrosine kinase (JAK2V617F) is present as an early somatic event in most patients with myeloproliferative neoplasms (MPNs), and the study of these chronic myeloid malignancies provides an experimentally tractable approach to understanding early tumorigenesis. Introduction of exogenous JAK2V617F impairs replication fork progression and is associated with activation of the intra-S checkpoint, with both effects mediated by phosphatidylinositide 3-kinase (PI3K) signaling. Analysis of clonally derived JAK2V617F-positive erythroblasts from MPN patients also demonstrated impaired replication fork progression accompanied by increased levels of replication protein A (RPA)-containing foci. However, the associated intra-S checkpoint response was impaired in erythroblasts from polycythemia vera (PV) patients, but not in those from essential thrombocythemia (ET) patients. Moreover, inhibition of p53 in PV erythroblasts resulted in more gamma-H2Ax (γ-H2Ax)-marked double-stranded breaks compared with in like-treated ET erythroblasts, suggesting the defective intra-S checkpoint function seen in PV increases DNA damage in the context of attenuated p53 signaling. These results demonstrate oncogene-induced impairment of replication fork progression in primary cells from MPN patients, reveal unexpected disease-restricted differences in activation of the intra-S checkpoint, and have potential implications for the clonal evolution of malignancies.
authors.affiliation: Cambridge Institute for Medical Research, Medical Research Council/Wellcome Trust Cambridge Stem Cell Institute, and Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom;
authors.forename: Edwin
authors.initials: E
authors.lastname: Chen
authors.affiliation: Cambridge Institute for Medical Research, Medical Research Council/Wellcome Trust Cambridge Stem Cell Institute, and Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom;
authors.forename: Jong Sook
authors.initials: JS
authors.lastname: Ahn
authors.affiliation: Cambridge Institute for Medical Research, Medical Research Council/Wellcome Trust Cambridge Stem Cell Institute, and Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom;
authors.forename: Charlie E
authors.initials: CE
authors.lastname: Massie
authors.affiliation: The Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom;
authors.forename: David
authors.initials: D
authors.lastname: Clynes
authors.affiliation: Cambridge Institute for Medical Research, Medical Research Council/Wellcome Trust Cambridge Stem Cell Institute, and Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom; Department of Haematology, Addenbrooke's Hospital, Cambridge CB2 0XY, United Kingdom; and.
authors.forename: Anna L
authors.initials: AL
authors.lastname: Godfrey
authors.affiliation: Cambridge Institute for Medical Research, Medical Research Council/Wellcome Trust Cambridge Stem Cell Institute, and Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom;
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.affiliation: Cambridge Institute for Medical Research, Medical Research Council/Wellcome Trust Cambridge Stem Cell Institute, and Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom;
authors.forename: Hyun Jung
authors.initials: HJ
authors.lastname: Park
authors.affiliation: Cambridge Institute for Medical Research, Medical Research Council/Wellcome Trust Cambridge Stem Cell Institute, and Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom; Department of Haematology, Addenbrooke's Hospital, Cambridge CB2 0XY, United Kingdom; and.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Nangalia
authors.affiliation: Cambridge Institute for Medical Research, Medical Research Council/Wellcome Trust Cambridge Stem Cell Institute, and Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom;
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Silber
authors.affiliation: Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115.
authors.forename: Ann
authors.initials: A
authors.lastname: Mullally
authors.affiliation: The Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom;
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Gibbons
authors.affiliation: Cambridge Institute for Medical Research, Medical Research Council/Wellcome Trust Cambridge Stem Cell Institute, and Department of Haematology, University of Cambridge, Cambridge CB2 0XY, United Kingdom; Department of Haematology, Addenbrooke's Hospital, Cambridge CB2 0XY, United Kingdom; and arg1000@cam.ac.uk.
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Green
mesh_terms: D017209:Apoptosis; D059447:Cell Cycle Checkpoints; D002455:Cell Division; D002875:Chromosomes / Q000378:metabolism / Q000648:ultrastructure; D004249:DNA Damage; D004260:DNA Repair; D004261:DNA Replication; D004171:Diploidy; D005347:Fibroblasts / Q000378:metabolism; D005838:Genotype; D006402:Hematologic Diseases / Q000235:genetics; D006801:Humans; D053614:Janus Kinase 2 / Q000235:genetics / Q000502:physiology*; D007938:Leukemia / Q000378:metabolism / Q000473:pathology; D008856:Microscopy, Fluorescence; D009196:Myeloproliferative Disorders / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation; D034741:RNA, Small Interfering / Q000378:metabolism; D016196:S Phase; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D034741:RNA, Small Interfering; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C507924:JAK2 protein, human; D053614:Janus Kinase 2
keywords: JAK2V617F; myeloproliferative neoplasm; replication stress