title: The human decatenation checkpoint.
abstract: Chromatid catenation is actively monitored in human cells, with progression from G(2) to mitosis being inhibited when chromatids are insufficiently decatenated. Mitotic delay was quantified in normal and checkpoint-deficient human cells during treatment with ICRF-193, a topoisomerase II catalytic inhibitor that prevents chromatid decatenation without producing topoisomerase-associated DNA strand breaks. Ataxia telangiectasia (A-T) cells, defective in DNA damage checkpoints, showed normal mitotic delay when treated with ICRF-193. The mitotic delay in response to ICRF-193 was ablated in human fibroblasts expressing an ataxia telangiectasia mutated- and rad3-related (ATR) kinase-inactive ATR allele (ATR(ki)). BRCA1-mutant HCC1937 cells also displayed a defect in ICRF-193-induced mitotic delay, which was corrected by expression of wild-type BRCA1. Phosphorylations of hCds1 or Chk1 and inhibition of Cdk1 kinase activity, which are elements of checkpoints associated with DNA damage or replication, did not occur during ICRF-193-induced mitotic delay. Over-expression of cyclin B1 containing a dominant nuclear localization signal, and inhibition of Crm1-mediated nuclear export, reversed ICRF-193-induced mitotic delay. In combination, these results imply that ATR and BRCA1 enforce the decatenation G(2) checkpoint, which may act to exclude cyclin B1/Cdk1 complexes from the nucleus. Moreover, induction of ATR(ki) produced a 10-fold increase in chromosomal aberrations, further emphasizing the vital role for ATR in genetic stability.
authors.affiliation: Department of Pathology and Laboratory Medicine and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: P B
authors.initials: PB
authors.lastname: Deming
authors.forename: C A
authors.initials: CA
authors.lastname: Cistulli
authors.forename: H
authors.initials: H
authors.lastname: Zhao
authors.forename: P R
authors.initials: PR
authors.lastname: Graves
authors.forename: H
authors.initials: H
authors.lastname: Piwnica-Worms
authors.forename: R S
authors.initials: RS
authors.lastname: Paules
authors.forename: C S
authors.initials: CS
authors.lastname: Downes
authors.forename: W K
authors.initials: WK
authors.lastname: Kaufmann
mesh_terms: D001260:Ataxia Telangiectasia; D064007:Ataxia Telangiectasia Mutated Proteins; D019313:BRCA1 Protein / Q000378:metabolism*; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D018797:Cell Cycle Proteins; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D019926:Cyclin B / Q000378:metabolism*; D056744:Cyclin B1; D004268:DNA-Binding Proteins; D054659:Diketopiperazines; D016195:G2 Phase; D006801:Humans; D008938:Mitosis / Q000187:drug effects / Q000502:physiology*; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D015398:Signal Transduction; D059005:Topoisomerase II Inhibitors; D025521:Tumor Suppressor Proteins
chemical_list: D019313:BRCA1 Protein; C534699:CCNB1 protein, human; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; D004268:DNA-Binding Proteins; D054659:Diketopiperazines; D010879:Piperazines; D059005:Topoisomerase II Inhibitors; D025521:Tumor Suppressor Proteins; C070899:4,4'-(1,2-dimethyl-1,2-ethanediyl)bis-2,6-piperazinedione; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C576324:ATM protein, human; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; C578634:CHEK2 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase