PMID- 9488036 OWN - NLM STAT- MEDLINE DCOM- 19980313 LR - 20211203 IS - 0950-9232 (Print) IS - 0950-9232 (Linking) VI - 16 IP - 6 DP - 1998 Feb 12 TI - Requirements for p53 and the ATM gene product in the regulation of G1/S and S phase checkpoints. PG - 721-36 AB - We investigated the requirements for protein p53 and the ATM gene product in radiation-induced inhibition of DNA synthesis and regulation of the cyclin E/ and cyclin A/cyclin dependent kinases (Cdks). Wild type (WT) mouse lung fibroblasts (MLFs), p53(-/-) knock-out MLFs, normal human skin fibroblasts (HSF-55), and human AT skin fibroblasts (GM02052) were used in the investigations. The absence of p53 had no significant effect on the inhibition or recovery of DNA synthesis throughout the S phase, as determined from BrdU labeling and flow cytometry, or the rapid inhibition of cyclin A/Cdks. Gamma radiation (8 Gy) inhibited DNA synthesis and progression into G2 during the first 3 h after irradiation, and the recovery of these processes occurred at similar rates in both WT and p53(-/-) MLFs. The cyclin A/Cdks were inhibited 55-70% at 1 h after irradiation in both cell types, but p21WAF1/Cip1 levels or p21 interaction with Cdk2 did not increase in the irradiated p53(-/-) MLFs. Although p53(-/-) MLFs do not exhibit prolonged arrest at a G1 checkpoint, radiation did induce a rapid 20% reduction and small super-recovery of cyclin E/Cdk2 within 1-2 h after irradiation. Similar inhibition and recovery of cyclin E/Cdk2 previously had been associated with regulation of transient G1 delay and the inhibition of initiation at an apparent G1/S checkpoint in Chinese hamster cells. In contrast, loss of the ATM gene product abrogated transient cyclin E/Cdk2 inhibition, most inhibition of DNA synthesis and all, but a 10-15% inhibition, of the cyclin A/Cdks. The results indicate that neither p53 nor p21 is required for transient inhibition of cyclin E/Cdk2 associated with the G1/S checkpoint or for inhibition of DNA synthesis at 'checkpoints' within the S phase. Conversely, the ATM gene product appears to be essential for regulation of the G1/S checkpoint and for inhibition of DNA replication associated with the inhibition of cyclin A/Cdk2. Differential aspects of DNA synthesis inhibition among cell types are presented and discussed in the context of S phase checkpoints. FAU - Xie, G AU - Xie G AD - The Life Sciences Division, Los Alamos National Laboratory, New Mexico 87545, USA. FAU - Habbersett, R C AU - Habbersett RC FAU - Jia, Y AU - Jia Y FAU - Peterson, S R AU - Peterson SR FAU - Lehnert, B E AU - Lehnert BE FAU - Bradbury, E M AU - Bradbury EM FAU - D'Anna, J A AU - D'Anna JA LA - eng GR - P41-RR01315/RR/NCRR NIH HHS/United States PT - Journal Article PT - Research Support, U.S. Gov't, Non-P.H.S. PT - Research Support, U.S. Gov't, P.H.S. PL - England TA - Oncogene JT - Oncogene JID - 8711562 RN - 0 (CDKN1A protein, human) RN - 0 (Cdkn1a protein, mouse) RN - 0 (Cell Cycle Proteins) RN - 0 (Cyclin E) RN - 0 (Cyclin-Dependent Kinase Inhibitor p21) RN - 0 (Cyclins) RN - 0 (DNA-Binding Proteins) RN - 0 (Proteins) RN - 0 (Tumor Suppressor Protein p53) RN - 0 (Tumor Suppressor Proteins) RN - 9007-49-2 (DNA) RN - EC 2.7.- (Protein Kinases) RN - EC 2.7.1.- (histone H1 kinase) RN - EC 2.7.11.1 (ATM protein, human) RN - EC 2.7.11.1 (Ataxia Telangiectasia Mutated Proteins) RN - EC 2.7.11.1 (Atm protein, mouse) RN - EC 2.7.11.1 (Protein Serine-Threonine Kinases) RN - EC 2.7.11.22 (CDC2 Protein Kinase) RN - EC 2.7.11.22 (CDC2-CDC28 Kinases) RN - EC 2.7.11.22 (CDK2 protein, human) RN - EC 2.7.11.22 (Cdk2 protein, mouse) RN - EC 2.7.11.22 (Cyclin-Dependent Kinase 2) RN - EC 2.7.11.22 (Cyclin-Dependent Kinases) SB - IM MH - Animals MH - Ataxia Telangiectasia/pathology MH - Ataxia Telangiectasia Mutated Proteins MH - CDC2 Protein Kinase/metabolism/radiation effects MH - *CDC2-CDC28 Kinases MH - CHO Cells MH - Cell Cycle Proteins MH - Cells, Cultured MH - Cricetinae MH - Cyclin E MH - Cyclin-Dependent Kinase 2 MH - Cyclin-Dependent Kinase Inhibitor p21 MH - Cyclin-Dependent Kinases/metabolism/radiation effects MH - Cyclins/metabolism/radiation effects MH - DNA/*biosynthesis MH - DNA Replication/radiation effects MH - DNA-Binding Proteins MH - Fibroblasts/cytology/*metabolism/radiation effects MH - G1 Phase MH - Gene Deletion MH - Humans MH - Mice MH - Mice, Inbred C57BL MH - Mice, Knockout MH - Protein Kinases/metabolism/radiation effects MH - Protein Serine-Threonine Kinases/metabolism/radiation effects MH - Proteins/*metabolism MH - S Phase MH - *Signal Transduction MH - Tumor Suppressor Protein p53/genetics/*metabolism MH - Tumor Suppressor Proteins EDAT- 1998/03/06 00:00 MHDA- 1998/03/06 00:01 CRDT- 1998/03/06 00:00 PHST- 1998/03/06 00:00 [pubmed] PHST- 1998/03/06 00:01 [medline] PHST- 1998/03/06 00:00 [entrez] AID - 10.1038/sj.onc.1201793 [doi] PST - ppublish SO - Oncogene. 1998 Feb 12;16(6):721-36. doi: 10.1038/sj.onc.1201793.