Abstract
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.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Ataxia Telangiectasia Mutated Proteins
-
Cell Cycle / drug effects*
-
Cell Cycle Proteins / physiology
-
Cell Hypoxia / drug effects
-
Cell Proliferation / drug effects
-
Cells, Cultured
-
Checkpoint Kinase 1
-
Checkpoint Kinase 2
-
Chromosomal Proteins, Non-Histone / physiology
-
DNA Damage / drug effects
-
DNA-Binding Proteins / physiology
-
Forkhead Box Protein O1
-
Forkhead Box Protein O3
-
Forkhead Transcription Factors / metabolism
-
Humans
-
Lymphocytes / drug effects*
-
Lymphocytes / physiology
-
Nuclear Proteins / physiology
-
Oxygen / pharmacology*
-
Phosphorylation
-
Protein Kinases / metabolism*
-
Protein Serine-Threonine Kinases / metabolism*
-
Protein Serine-Threonine Kinases / physiology
-
Signal Transduction / drug effects
-
Tumor Suppressor Protein p53 / metabolism*
-
Tumor Suppressor Proteins / physiology
Substances
-
Cell Cycle Proteins
-
Chromosomal Proteins, Non-Histone
-
DNA-Binding Proteins
-
FOXO1 protein, human
-
FOXO3 protein, human
-
Forkhead Box Protein O1
-
Forkhead Box Protein O3
-
Forkhead Transcription Factors
-
NBN protein, human
-
Nuclear Proteins
-
Tumor Suppressor Protein p53
-
Tumor Suppressor Proteins
-
structural maintenance of chromosome protein 1
-
Protein Kinases
-
Checkpoint Kinase 2
-
ATM protein, human
-
Ataxia Telangiectasia Mutated Proteins
-
CHEK1 protein, human
-
CHEK2 protein, human
-
Checkpoint Kinase 1
-
Protein Serine-Threonine Kinases
-
Oxygen