title: The nucleolus stress response is coupled to an ATR-Chk1-mediated G2 arrest.
abstract: We report experiments on the connection between nucleolar stress and cell cycle progression, using HeLa cells engineered with the fluorescent ubiquitinylation-based cell cycle indicator. Nucleolar stress elicited by brief exposure of cells to a low concentration of actinomycin D that selectively inhibits rRNA synthesis had no effect on traverse of G1 or S, but stalled cells in very late interphase. Additional experiments revealed that a switch occurs during a specific temporal window during nucleolar stress and that the subsequent cell cycle arrest is not triggered simply by the stress-induced decline in the synthesis of rRNA or by a ribosome starvation phenomenon. Further experiments revealed that this nucleolus stress-induced cell cycle arrest involves the action of a G2 checkpoint mediated by the ataxia telangiectasia and Rad3-related protein (ATR)-checkpoint kinase 1 (Chk1) pathway. Based on analysis of the cell cycle stages at which this nucleolar stress effect is put into action, to become manifest later, our results demonstrate a feedforward mechanism that leads to G2 arrest and identify ATR and Chk1 as molecular agents of the requisite checkpoint.
authors: Department of Biochemistry and Molecular Pharmacology and Program in Cell and Developmental Dynamics, University of Massachusetts Medical School, Worcester, MA 01605, USA. hanhui.ma@umassmed.edu
authors: Hanhui
authors: H
authors: Ma
authors: Thoru
authors: T
authors: Pederson
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D002110:Caffeine / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002466:Cell Nucleolus / Q000502:physiology*; D000071877:Checkpoint Kinase 1; D004249:DNA Damage; D003609:Dactinomycin / Q000494:pharmacology; D059565:G2 Phase Cell Cycle Checkpoints; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D059010:Single-Cell Analysis; D013312:Stress, Physiological
chemical_list: D018797:Cell Cycle Proteins; C468783:H2AX protein, human; D006657:Histones; D011500:Protein Synthesis Inhibitors; D003609:Dactinomycin; D002110:Caffeine; D011494:Protein Kinases; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases