DNA methylation in human fibroblasts following DNA damage and repair

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:6264756

Kastan, M B

Methylation of deoxycytidine (dCyd) incorporated by DNA excision repair synthesis in human diploid fibroblasts following damage with ultraviolet radiation (UV), N-methyl-N-nitrosourea, or N-acetoxy-2-acetylaminofluorene was studied utilizing (6-/sup 3/H)dCyd to label repaired DNA specifically and high performance liquid chromatographic analysis to quantify the percentage of deoxycytidine converted to 5-methyldeoxycytidine (m/sup 5/dCyd). In confluent, nondividing cells, methylation in repair patches induced by all three agents is slow and incomplete. Whereas after DNA replication a level of 3.4% m/sup 5/dCyd is reached in less than 2 hours, following UV-stimulated repair synthesis in confluent cells it takes about 3 days to reach a level of approx.2.0% m/sup 5/dCyd in the repair patch. This undermethylation of repair patches occurs throughout the genome. In cells from cultures in logarithmic-phase growth, m/sup 5/dCyd formation in UV-induced repair patches occurs faster and to a greater extent, reaching a level of approx.2.7% in 10-20 hours. Pre-existing hypomethylated repair patches in confluent cells are methylated further when the cells are stimulated to divide; however, the repair patch may still not be fully methylated before cell division occurs. Thus DNA damage and repair may lead to heritable loss of methylation at some sites. The distribution within chromatin of m/sup 5/dCyd in repair patches was also investigated. Over a wide range of extents of digestion by staphylococcal nuclease or deoxyribonuclease I, the level of hypomethylation in repaired DNA in nuclease sensitive and resistant regions of chromatin was constant relative to the genomic level of methylation in these regions. Similar conclusions were reached in experiments with isolated mononucleosomes.

• Research Organization: Washington Univ., St. Louis, MO (USA)
• OSTI ID: 6264756
• Country of Publication: United States
• Language: English

Related Subjects

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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
AZINES
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CELL DIVISION
CHEMICAL REACTIONS
CHROMATIN
CONNECTIVE TISSUE CELLS
DEOXYCYTIDINE
DNA
DNA REPAIR
DNA REPLICATION
ELECTROMAGNETIC RADIATION
ELEMENTS
ENZYMES
ESTERASES
FIBROBLASTS
FLUORINE
GENETIC EFFECTS
GENETIC RADIATION EFFECTS
HALOGENS
HETEROCYCLIC COMPOUNDS
HYDROLASES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
METHYLATION
MITOSIS
NITROSO COMPOUNDS
NITROSOUREAS
NONMETALS
NUCLEASES
NUCLEIC ACID REPLICATION
NUCLEIC ACIDS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOSPHODIESTERASES
PYRIMIDINES
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
RIBOSIDES
SOMATIC CELLS
TOXICITY
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ULTRAVIOLET RADIATION