Figure 2: p53 drives p21 heterogeneity in unperturbed conditions. | Nature Communications

Figure 2: p53 drives p21 heterogeneity in unperturbed conditions.

From: DNA damage during S-phase mediates the proliferation-quiescence decision in the subsequent G1 via p21 expression

Figure 2

(a) p21-GFP levels versus G1 length after siRNA treatment: control siRNA (blue), n=75 cells; p53 siRNA (yellow), n=81; or p21 siRNA (red), n=90. (b) Percentage of cells arresting in G1 for three siRNA treatments and for p21WT versus two p21KO clones. Number of cells is shown above each bar. Red bars represent cells that enter G1pm arrest, blue bars are cells that enter S-phase (cycle). (c) Single-cell traces of p21-GFP levels after 5 μM Nutlin-3 addition: S-phase on addition, yellow, n=8 cells; G1 on addition, blue, n=8. Time of mitosis is marked by black circles and time of S-phase entry is marked by blue circles on each single-cell trace. (d) Effect of rate of p21-GFP accumulation on G2 entry after Nutlin-3 addition to cells in S-phase. Black circles represent mitosis. Arrest, red, n=19 cells; Mitosis, blue, n=28. (e) CDK2 activity profiles aligned to mitosis for: control siRNA, n=51 cells; p21 siRNA, n=68 cells; and p53 siRNA, n=25 cells. Red curves represent CDK2low cells. Black circles represent time of S-phase entry. (f) Single-cell trace of CDK2 activity and p21-GFP levels in an unperturbed cell. Brown shading is G2. Grey shading shows a period in G1 where CDK2 activity is increasing despite expression of p21-GFP. Traces aligned to S-phase entry at t=0 min. p21-GFP levels are shown in green and CDK2 activity is shown in red. (g) Single-cell trace of CDK2 activity and p21-GFP levels in an unperturbed cell arrested in G1. p21-GFP levels are shown in green and CDK2 activity is shown in red. Note: different scale for p21-GFP y-axis compared to (f).

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