Image-Based Modeling Reveals Dynamic Redistribution of DNA Damageinto Nuclear Sub-Domains

Journal Article · Fri Aug 03 04:00:00 EDT 2007 · PLoS Computational Biology

OSTI ID:926893

Nguyen, David; Cucinotta, Francis A; Barcellos-Hoff, Mary Helen

Several proteins involved in the response to DNA doublestrand breaks (DSB) f orm microscopically visible nuclear domains, orfoci, after exposure to ionizing radiation. Radiation-induced foci (RIF)are believed to be located where DNA damage occurs. To test thisassumption, we analyzed the spatial distribution of 53BP1, phosphorylatedATM, and gammaH2AX RIF in cells irradiated with high linear energytransfer (LET) radiation and low LET. Since energy is randomly depositedalong high-LET particle paths, RIF along these paths should also berandomly distributed. The probability to induce DSB can be derived fromDNA fragment data measured experimentally by pulsed-field gelelectrophoresis. We used this probability in Monte Carlo simulations topredict DSB locations in synthetic nuclei geometrically described by acomplete set of human chromosomes, taking into account microscope opticsfrom real experiments. As expected, simulations produced DNA-weightedrandom (Poisson) distributions. In contrast, the distributions of RIFobtained as early as 5 min after exposure to high LET (1 GeV/amu Fe) werenon-random. This deviation from the expected DNA-weighted random patterncan be further characterized by "relative DNA image measurements." Thisnovel imaging approach shows that RIF were located preferentially at theinterface between high and low DNA density regions, and were morefrequent than predicted in regions with lower DNA density. The samepreferential nuclear location was also measured for RIF induced by 1 Gyof low-LET radiation. This deviation from random behavior was evidentonly 5 min after irradiation for phosphorylated ATM RIF, while gammaH2AXand 53BP1 RIF showed pronounced deviations up to 30 min after exposure.These data suggest that DNA damage induced foci are restricted to certainregions of the nucleus of human epithelial cells. It is possible that DNAlesions are collected in these nuclear sub-domains for more efficientrepair.

• Research Organization: Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
• Sponsoring Organization: USDOE Director, Office of Science; National Aeronautics andSpace Administration
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 926893
• Report Number(s): LBNL--62387; BnR: 400409900
• Journal Information: PLoS Computational Biology, Journal Name: PLoS Computational Biology Journal Issue: 7 Vol. 3
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
59 BASIC BIOLOGICAL SCIENCES
61 RADIATION PROTECTION AND DOSIMETRY
DNA
DNA DAMAGES
DNA damage center of repair nuclear organization
ELECTROPHORESIS
HUMAN CHROMOSOMES
IONIZING RADIATIONS
IRRADIATION
LET
MICROSCOPES
NUCLEI
OPTICS
PROBABILITY
PROTEINS
RADIATIONS
REPAIR
SIMULATION
SPATIAL DISTRIBUTION