Cytometric Assessment of DNA Damage Induced by DNA Topoisomerase Inhibitors
Exposure of cells to inhibitors of DNA topoisomerase I (topo I) or topoisomerase II (topo II) leads to DNA damage that often involves formation of DNA double-strand breaks (DSBs). DNA damage, particularly induction of DSBs, manifests by phosphorylation of histone H2AX on Ser- 139 which is mediated by one of the protein kinases of the phosphoinositide kinase family, namely ATM, ATR, and/or DNA-PK. The presence of Ser -139 phosphorylated H2AX (γH2AX) is thus a reporter of DNA damage. This protocol describes quantitative assessment of γH2AX detected immunocytochemically in individual cells combined with quantification of cellular DNA content by cytometry. The bivariate analysis of γH2AX expression versus DNA content allows one to correlate DNA damage with the cell cycle phase or DNA ploidy. The protocol can also be used to assess activation (Ser- 1981 phosphorylation) of ATM; this event also revealing DNA damage induced by topo I or topo II inhibitors. Examples where DNA damage was induced by topotecan (topo I) and etoposide (topo II) inhibitors are provided.
- Methylated DNA Immunoprecipitation (MeDIP) from Low Amounts of Cells
- Multigenerational Selection and Detection of Altered Histone Acetylation and Methylation Patterns: Toward a Quantitative Epigene
- DNA Diagnostics and Exon Skipping
- Composition-Based Methods to Identify Horizontal Gene Transfer
- Direct Analysis of Chromosome Methylation
- Comparative Genomic Hybridization: Microarray Design and Data Interpretation
- RNAi in the Malaria Vector, Anopheles gambiae
- Reverse Chromosome Painting
- Monitoring B Cell Response to Immunoselected Phage-Displayed Peptides by Microarrays
- Asking Complex Questions of the Genome Without Programming