Reoxygenation following hypoxia activates DNA-damage checkpoint signaling pathways that suppress cell-cycle progression in cultured human lymphocytes.
Cellular responses to DNA damage after hypoxia and reoxygenation (H/R) were examined in human lymphocytes. Cultured lymphocytes exposed to H/R showed a lower cytokinesis block proliferation index and a higher frequency of micronuclei in comparison to control cells. Western blots showed that H/R exposure induced p53 expression; however, p21 and Bax expression did not increase, indicating that H/R did not affect p53 transactivational activity. Phosphorylation of p53 (Ser15), Chk1 (Ser345), and Chk2 (Thr68) was also observed, suggesting that H/R activates p53 through checkpoint signals. In addition, H/R exposure caused the phosphorylation and negative regulation of Cdc2 and Cdc25C, proteins that are involved in cell-cycle arrest at the G2/M checkpoint. The S-phase checkpoint, regulated by the ATM-p95/NBS1-SMC1 pathway, was also triggered in H/R-exposed lymphocytes. These results demonstrate that H/R exposure triggers checkpoint signaling and induces cell-cycle arrest in cultured human lymphocytes.
Kim
Byeong-Mo
BM
School of Public Health and Institute of Health and Environment, Seoul National University, Seoul, Republic of Korea.
Choi
Jun Yeol
JY
Kim
Yang-Jee
YJ
Woo
Hae-Dong
HD
Chung
Hai Won
HW
D064007:Ataxia Telangiectasia Mutated Proteins; D002453:Cell Cycle / Q000187:drug effects*; D018797:Cell Cycle Proteins / Q000502:physiology; D015687:Cell Hypoxia / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D002868:Chromosomal Proteins, Non-Histone / Q000502:physiology; D004249:DNA Damage / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000502:physiology; D000071161:Forkhead Box Protein O1; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000378:metabolism; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects* / Q000502:physiology; D009687:Nuclear Proteins / Q000502:physiology; D010100:Oxygen / Q000494:pharmacology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000502:physiology; D000098550:Structural Maintenance of Chromosome Protein 1
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; C085126:FOXO1 protein, human; C499517:FOXO3 protein, human; D000071161:Forkhead Box Protein O1; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; C112156:NBN protein, human; D009687:Nuclear Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D000098550:Structural Maintenance of Chromosome Protein 1; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; C578634:CHEK2 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; D010100:Oxygen