Induction and quantification of gamma-H2AX foci following low and high LET-irradiation.
OBJECTIVE
To investigate quantitatively the induction and rejoining of DNA double strand breaks (DSB) in V79-4 and xrs-5 Chinese hamster cells and HF19 human fibroblast cells, using the phosphorylation of the histone protein H2AX (gamma-H2AX) as an indicator of DSB, exposed to low doses of either low linear energy transfer (LET) (60)Co gamma-rays or high LET a-particles.


METHODS
Cells were irradiated with low or high LET (20 - 2000 mGy). The gamma-H2AX foci were detected using immunohistochemistry and quantified by image analysis.


RESULTS
The number of DSB determined 30 min post gamma-irradiation at 37 degrees C is 12.2 (+/-1.5), 13.5 (+/-1.6) and 19.1 (+/-1.7) foci/cell/Gy for V79-4, xrs-5 and HF19 cells respectively, comparable with levels detected in V79-4 cells using pulse field gel electrophoresis. 6 h post gamma-irradiation, gamma-H2AX foci levels in V79-4 and HF19 cells approach control levels but remain higher in DSB repair deficient xrs-5 cells. Gamma-H2AX foci levels remain significantly higher than controls at 6 h in a-irradiated cells.


CONCLUSIONS
Gamma-radiation and alpha-radiation induced the phosphorylation of H2AX in response to DSB at low doses; the variation in the rate of dephosphorylation of induced foci are dependent both on radiation quality and cell characteristics.
Leatherbarrow
Emma L
EL
DNA Damage Group, Radiation and Genome Stability Unit, Medical Research Council, Harwell, Oxfordshire, UK.
Harper
Jane V
JV
Cucinotta
Francis A
FA
O'Neill
Peter
P
D000512:Alpha Particles; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000528:radiation effects*; D005720:Gamma Rays; D006657:Histones / Q000235:genetics* / Q000528:radiation effects*; D006801:Humans; D018499:Linear Energy Transfer; D011829:Radiation Dosage
C468783:H2AX protein, human; D006657:Histones; D004247:DNA