title: Nek4 regulates entry into replicative senescence and the response to DNA damage in human fibroblasts.
abstract: When explanted into culture, normal human cells exhibit a finite number of cell divisions before entering a proliferative arrest termed replicative senescence. To identify genes essential for entry into replicative senescence, we performed an RNA interference (RNAi)-based loss-of-function screen and found that suppression of the Never in Mitosis Gene A (NIMA)-related protein kinase gene NEK4 disrupted timely entry into senescence. NEK4 suppression extended the number of population doublings required to reach replicative senescence in several human fibroblast strains and resulted in decreased transcription of the cyclin-dependent kinase inhibitor p21. NEK4-suppressed cells displayed impaired cell cycle arrest in response to double-stranded DNA damage, and mass spectrometric analysis of Nek4 immune complexes identified a complex containing DNA-dependent protein kinase catalytic subunit [DNA-PK(cs)], Ku70, and Ku80. NEK4 suppression causes defects in the recruitment of DNA-PK(cs) to DNA upon induction of double-stranded DNA damage, resulting in reduced p53 activation and H2AX phosphorylation. Together, these observations implicate Nek4 as a novel regulator of replicative senescence and the response to double-stranded DNA damage.
authors.affiliation: Department of Medical Oncology, Dana-Farber Cancer Institute and Department of Medicine, Harvard Medical School, Boston, MA, USA.
authors.forename: Christine L
authors.initials: CL
authors.lastname: Nguyen
authors.forename: Richard
authors.initials: R
authors.lastname: Possemato
authors.forename: Erica L
authors.initials: EL
authors.lastname: Bauerlein
authors.forename: Anyong
authors.initials: A
authors.lastname: Xie
authors.forename: Ralph
authors.initials: R
authors.lastname: Scully
authors.forename: William C
authors.initials: WC
authors.lastname: Hahn
mesh_terms: D059447:Cell Cycle Checkpoints; D002460:Cell Line; D049109:Cell Proliferation; D002478:Cells, Cultured; D016922:Cellular Senescence; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D051747:DNA-Activated Protein Kinase / Q000378:metabolism; D015536:Down-Regulation; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D000072379:NIMA-Related Kinases; D060066:Protein Interaction Maps; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D004247:DNA; D051747:DNA-Activated Protein Kinase; D000072379:NIMA-Related Kinases; D017346:Protein Serine-Threonine Kinases; D019098:Telomerase; C493956:CDKN1A protein, human; C547589:NEK4 protein, human