The Human Decatenation Checkpoint

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 98; no. 21; pp. 12044 - 12049
• Main Authors: Deming, Paula B., Cistulli, Cheryl A., Zhao, Hui, Graves, Paul R., Piwnica-Worms, Helen, Paules, Richard S., Downes, C. Stephen, Kaufmann, William K.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 09.10.2001; National Acad Sciences; The National Academy of Sciences
• Subjects: Ataxia Telangiectasia; Ataxia Telangiectasia Mutated Proteins; ATR protein; Biological Sciences; BRCA1 protein; BRCA1 Protein - metabolism; CDC2 Protein Kinase - metabolism; Cdk1 kinase; Cell cycle; Cell Cycle Proteins; Cell Line; Cell lines; Cell nucleus; Cell Nucleus - metabolism; Cells; Cellular biology; Checkpoint Kinase 1; Checkpoint Kinase 2; Chromatids; Cyclin B - metabolism; Cyclin B1; Cyclins; Deoxyribonucleic acid; Diketopiperazines; DNA; DNA damage; DNA-Binding Proteins; Enzymes; G2 Phase; Genetics; HeLa cells; Humans; ICRF-193; Mitosis; Mitosis - drug effects; Mitosis - physiology; Phosphorylation; Piperazines - pharmacology; Protein Kinases - metabolism; Protein Serine-Threonine Kinases - metabolism; Signal Transduction; Topoisomerase II Inhibitors; Tumor Suppressor Proteins
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.221430898

Chromatid catenation is actively monitored in human cells, with progression from G2to 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 (ATRki). 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 G2checkpoint, which may act to exclude cyclin B1/Cdk1 complexes from the nucleus. Moreover, induction of ATRkiproduced a 10-fold increase in chromosomal aberrations, further emphasizing the vital role for ATR in genetic stability.