Formation and repair of DNA double-strand breaks in gamma-irradiated K562 cells undergoing erythroid differentiation

TY - JOUR

T1 - Formation and repair of DNA double-strand breaks in gamma-irradiated K562 cells undergoing erythroid differentiation

AU - Tabocchini, M A

AU - Rothkamm, K

AU - Signoretti, C

AU - Risse, J

AU - Sapora, O

AU - Löbrich, M

PY - 2000/9/15

Y1 - 2000/9/15

N2 - Cellular differentiation is accompanied by gross changes in nuclear organization, metabolic pathways and gene expression characteristics. To investigate, whether the response to radiation damage is altered during cellular differentiation, we studied the formation and repair of DNA double-strand breaks in gamma-irradiated K562 erythroleukemia cells induced to differentiate by exposure to butyric acid. We applied an assay based on pulsed-field gel electrophoresis and Southern hybridization to measure break induction in several genomic restriction fragments. Pulsed-field gel electrophoresis of (14)C-labelled unrestricted DNA was used to study the rejoining of gamma-radiation-induced breaks in the whole genome. Total rejoining and joining of correct break ends in specific genomic regions was monitored by hybridization analysis of blots of unrestricted and restriction digested DNA with single-copy probes. The yields of gamma-ray-induced DNA double-strand breaks were found to decrease with differentiation by about 20%. Correct rejoining of radiation-induced breaks, as measured by the reconstitution of broken restriction fragments, was unaltered in differentiating cells compared to actively proliferating precursor cells. Total rejoining, however, appeared to be retarded in differentiating cells. The results suggest that in spite of the fundamental changes accompanying differentiation, the cellular damage response pathways are not essentially affected throughout erythroid differentiation.

AB - Cellular differentiation is accompanied by gross changes in nuclear organization, metabolic pathways and gene expression characteristics. To investigate, whether the response to radiation damage is altered during cellular differentiation, we studied the formation and repair of DNA double-strand breaks in gamma-irradiated K562 erythroleukemia cells induced to differentiate by exposure to butyric acid. We applied an assay based on pulsed-field gel electrophoresis and Southern hybridization to measure break induction in several genomic restriction fragments. Pulsed-field gel electrophoresis of (14)C-labelled unrestricted DNA was used to study the rejoining of gamma-radiation-induced breaks in the whole genome. Total rejoining and joining of correct break ends in specific genomic regions was monitored by hybridization analysis of blots of unrestricted and restriction digested DNA with single-copy probes. The yields of gamma-ray-induced DNA double-strand breaks were found to decrease with differentiation by about 20%. Correct rejoining of radiation-induced breaks, as measured by the reconstitution of broken restriction fragments, was unaltered in differentiating cells compared to actively proliferating precursor cells. Total rejoining, however, appeared to be retarded in differentiating cells. The results suggest that in spite of the fundamental changes accompanying differentiation, the cellular damage response pathways are not essentially affected throughout erythroid differentiation.

KW - Butyrates/pharmacology

KW - Cell Cycle

KW - Cell Differentiation/radiation effects

KW - DNA Damage

KW - DNA Repair

KW - Erythropoiesis/radiation effects

KW - Gamma Rays/adverse effects

KW - Genome

KW - Humans

KW - K562 Cells

U2 - 10.1016/s0921-8777(00)00041-0

DO - 10.1016/s0921-8777(00)00041-0

M3 - SCORING: Journal article

C2 - 10980413

VL - 461

SP - 71

EP - 82

IS - 1

ER -