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.
DNA Damage Group, Radiation and Genome Stability Unit, Medical Research Council, Harwell, Oxfordshire, UK.
Emma L
EL
Leatherbarrow
Jane V
JV
Harper
Francis A
FA
Cucinotta
Peter
P
O'Neill
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