Figure 3. Persistent DDR is physically associated with telomeric DNA.

a. Chromosomal view of the enrichment of γH2AX in IrrSen vs Quie cells. Individual chromosomes representation of the enrichment of γH2AX in IrrSen BJ hTERT cells. Grey arrows indicate the highest peak of each chromosome arm within 5 Mbp from a chromosome end. b. Enrichment of γH2AX in IrrSen vs Quie cells at chromosome ends. Solid line represents the accumulation pattern of γH2AX over 20 Mbp from the chromosomes end. The profile shows an enrichment peak at the most terminal region (0–5 Mbp). The enrichment is significantly different when compared to the accumulation in a more internal region (15–20 Mbp), (Mann-Whitney-U p-value = 0, n=2.3e6). 95% credibility intervals are shown as dashed lines; a.u. means arbitrary units. c. Increasing amounts of antibodies against γH2AX immunoprecipitate increasing amounts of subtelomeric DNA from IrrSen BJ cells compared to non-irradiated Quie cells, as assayed on telomere 12p by ChIP and qPCR using a primer pair distant 95 Kb from chromosome end. Triplicate qPCR reactions were carried out and the averaged results are plotted as the log2 ratio between IP and input (n = 2). d. γH2AX and subtelomeric DNA are physically associated in IrrSen BJ cells. Enrichment of γH2AX was assayed on telomere 12p by ChIP and qPCR with previously independently-validated primer pairs¹⁹ at indicated increasing distances from the chromosome end. Graph shows subtracted log2 ratios between IP and input of IrrSen minus Quie cells (diff log2 ratio). Triplicate qPCR reactions were carried out and the averaged results are plotted (n = 2).