Linked Life Data

2537462

Source:http://linkedlifedata.com/resource/pubmed/id/2537462

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1989-3-29
pubmed:abstractText
The role of topoisomerase enzymes in the response of HeLa S3 cells to ionizing radiation was investigated. Exposure of cells to 100 Gy of X-radiation had no detectable effect either on the total cellular topoisomerase activity as measured by the relaxation of supercoiled plasmid DNA by cell sonicates or on the total cellular topoisomerase II activity as measured by plasmid DNA catenation. Total topoisomerase II activity remained constant for up to 90 min after cell irradiation. The effect of 2 drugs (caffeine and novobiocin) which inhibit topoisomerase II activity on the HeLa cell response to radiation was determined. Both drugs were found to inhibit topoisomerase II in vitro and to inhibit the recovery of nucleoid sedimentation in irradiated cells in vivo to the same extent. Topoisomerase II was inhibited by 50% by exposure to 10 mM caffeine and 0.79 mM novobiocin. At low concentrations neither drug affected the induction frequency, nor the rejoining rate, of DNA double-strand breaks. Caffeine (5 mM) inhibited the short-term recovery of cells from radiation while novobiocin (0.79 mM) had no detectable effect on the capacity of cells to recover from radiation exposure. The results indicate that topoisomerase II is not required for DNA double-strand break rejoining though it could be required for the recovery of DNA coiling in the irradiated cell. If topoisomerase II is involved at all in cell recovery from irradiation, this role does not apparently involve an ATP-dependent enzyme activity.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0027-5107
pubmed:author
pubmed:issnType
Print
pubmed:volume
216
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
43-55
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Topoisomerase activity in irradiated mammalian cells.
pubmed:affiliation
Department of Radiology, University of Utah Health Sciences Center, Salt Lake 84132.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.